diff --git a/FWCore/Integration/test/ProducerWithPSetDesc.cc b/FWCore/Integration/test/ProducerWithPSetDesc.cc
index 510c63e6e365b..f9638e1cd6828 100644
--- a/FWCore/Integration/test/ProducerWithPSetDesc.cc
+++ b/FWCore/Integration/test/ProducerWithPSetDesc.cc
@@ -4,7 +4,6 @@
 #include "FWCore/Framework/interface/MakerMacros.h"
 
 #include "FWCore/ParameterSet/interface/ConfigurationDescriptions.h"
-#include "FWCore/ParameterSet/interface/getFixedSizeArray.h"
 #include "FWCore/ParameterSet/interface/ParameterSetDescription.h"
 #include "FWCore/ParameterSet/interface/ParameterDescriptionBase.h"
 #include "FWCore/ParameterSet/interface/ParameterDescription.h"
@@ -80,10 +79,10 @@ namespace edmtest {
     vint = ps.getParameter<std::vector<int>>("vint3");
     assert(vint[0] == 2147483647);
     assert(vint[1] == -2147483647);
-    std::array<int, 2> testArray = edm::getFixedSizeArray<int, 2>(ps, std::string("vint3"));
+    std::array<int, 2> testArray = ps.getParameter<std::array<int, 2>>(std::string("vint3"));
     assert(testArray[0] == 2147483647);
     assert(testArray[1] == -2147483647);
-    std::array<int, 2> testArray1 = edm::getFixedSizeArray<int, 2>(ps, "vint3");
+    std::array<int, 2> testArray1 = ps.getParameter<std::array<int, 2>>("vint3");
     assert(testArray1[0] == 2147483647);
     assert(testArray1[1] == -2147483647);
     vint = ps.getParameter<std::vector<int>>("vint4");
diff --git a/FWCore/ParameterSet/interface/ParameterSet.h b/FWCore/ParameterSet/interface/ParameterSet.h
index fff95f284c685..bb4421ac615b8 100644
--- a/FWCore/ParameterSet/interface/ParameterSet.h
+++ b/FWCore/ParameterSet/interface/ParameterSet.h
@@ -22,6 +22,7 @@
 #include <memory>
 #include <string>
 #include <vector>
+#include <array>
 
 // ----------------------------------------------------------------------
 // contents
@@ -33,6 +34,16 @@ namespace edm {
   class ModuleDescription;
   typedef std::vector<ParameterSet> VParameterSet;
 
+  template <typename T>
+  struct ParameterTypeTraits {
+    //When specializing the template, include the following in the struct:
+    //
+    // using GetType = <underlying parameter type to get from the ParameterSet>;
+    //
+    // //Function to convert the parameter type into the requested type
+    // static T convert(GetType, std::string const&);
+  };
+
   class ParameterSet {
   public:
     template <typename T>
@@ -288,8 +299,36 @@ namespace edm {
 
   ParameterSet const& getProcessParameterSetContainingModule(ModuleDescription const& moduleDescription);
 
+  template <typename T>
+  inline T ParameterSet::getParameter(std::string const& name) const {
+    using GetType = typename ParameterTypeTraits<T>::GetType;
+    return ParameterTypeTraits<T>::convert(getParameter<GetType>(name), name);
+  }
+
+  template <typename T>
+  inline T ParameterSet::getParameter(const char* name) const {
+    using GetType = typename ParameterTypeTraits<T>::GetType;
+    return ParameterTypeTraits<T>::convert(getParameter<GetType>(name), name);
+  }
   // specializations
   // ----------------------------------------------------------------------
+  namespace pset::exceptions {
+    void throwWrongNumberOfElements(std::string const& iParameterName, size_t iExpected, size_t iGot);
+  }
+  //Read an std::array from an std::vector
+  template <typename T, std::size_t N>
+  struct ParameterTypeTraits<std::array<T, N>> {
+    using GetType = std::vector<T>;
+    static std::array<T, N> convert(std::vector<T> iVec, std::string const& iName) {
+      if (iVec.size() != N) {
+        pset::exceptions::throwWrongNumberOfElements(iName, N, iVec.size());
+      }
+      std::array<T, N> a;
+      std::copy_n(std::make_move_iterator(iVec.begin()), N, a.begin());
+      return a;
+    }
+  };
+  // ----------------------------------------------------------------------
 
   template <>
   bool ParameterSet::getParameter<bool>(std::string const& name) const;
@@ -301,7 +340,7 @@ namespace edm {
   int ParameterSet::getParameter<int>(std::string const& name) const;
 
   template <>
-  std::vector<int> ParameterSet::getParameter<std::vector<int> >(std::string const& name) const;
+  std::vector<int> ParameterSet::getParameter<std::vector<int>>(std::string const& name) const;
 
   // ----------------------------------------------------------------------
   // Int64, vInt64
@@ -310,7 +349,7 @@ namespace edm {
   long long ParameterSet::getParameter<long long>(std::string const& name) const;
 
   template <>
-  std::vector<long long> ParameterSet::getParameter<std::vector<long long> >(std::string const& name) const;
+  std::vector<long long> ParameterSet::getParameter<std::vector<long long>>(std::string const& name) const;
 
   // ----------------------------------------------------------------------
   // Uint32, vUint32
@@ -319,7 +358,7 @@ namespace edm {
   unsigned int ParameterSet::getParameter<unsigned int>(std::string const& name) const;
 
   template <>
-  std::vector<unsigned int> ParameterSet::getParameter<std::vector<unsigned int> >(std::string const& name) const;
+  std::vector<unsigned int> ParameterSet::getParameter<std::vector<unsigned int>>(std::string const& name) const;
 
   // ----------------------------------------------------------------------
   // Uint64, vUint64
@@ -328,7 +367,7 @@ namespace edm {
   unsigned long long ParameterSet::getParameter<unsigned long long>(std::string const& name) const;
 
   template <>
-  std::vector<unsigned long long> ParameterSet::getParameter<std::vector<unsigned long long> >(
+  std::vector<unsigned long long> ParameterSet::getParameter<std::vector<unsigned long long>>(
       std::string const& name) const;
 
   // ----------------------------------------------------------------------
@@ -338,7 +377,7 @@ namespace edm {
   double ParameterSet::getParameter<double>(std::string const& name) const;
 
   template <>
-  std::vector<double> ParameterSet::getParameter<std::vector<double> >(std::string const& name) const;
+  std::vector<double> ParameterSet::getParameter<std::vector<double>>(std::string const& name) const;
 
   // ----------------------------------------------------------------------
   // String, vString
@@ -347,7 +386,7 @@ namespace edm {
   std::string ParameterSet::getParameter<std::string>(std::string const& name) const;
 
   template <>
-  std::vector<std::string> ParameterSet::getParameter<std::vector<std::string> >(std::string const& name) const;
+  std::vector<std::string> ParameterSet::getParameter<std::vector<std::string>>(std::string const& name) const;
 
   // ----------------------------------------------------------------------
   // FileInPath
@@ -370,7 +409,7 @@ namespace edm {
   // VInputTag
 
   template <>
-  std::vector<InputTag> ParameterSet::getParameter<std::vector<InputTag> >(std::string const& name) const;
+  std::vector<InputTag> ParameterSet::getParameter<std::vector<InputTag>>(std::string const& name) const;
 
   // ----------------------------------------------------------------------
   // ESInputTag
@@ -382,7 +421,7 @@ namespace edm {
   // VESInputTag
 
   template <>
-  std::vector<ESInputTag> ParameterSet::getParameter<std::vector<ESInputTag> >(std::string const& name) const;
+  std::vector<ESInputTag> ParameterSet::getParameter<std::vector<ESInputTag>>(std::string const& name) const;
 
   // ----------------------------------------------------------------------
   // EventID
@@ -394,7 +433,7 @@ namespace edm {
   // VEventID
 
   template <>
-  std::vector<EventID> ParameterSet::getParameter<std::vector<EventID> >(std::string const& name) const;
+  std::vector<EventID> ParameterSet::getParameter<std::vector<EventID>>(std::string const& name) const;
 
   // ----------------------------------------------------------------------
   // LuminosityBlockID
@@ -406,7 +445,7 @@ namespace edm {
   // VLuminosityBlockID
 
   template <>
-  std::vector<LuminosityBlockID> ParameterSet::getParameter<std::vector<LuminosityBlockID> >(
+  std::vector<LuminosityBlockID> ParameterSet::getParameter<std::vector<LuminosityBlockID>>(
       std::string const& name) const;
 
   // ----------------------------------------------------------------------
@@ -419,7 +458,7 @@ namespace edm {
   // VEventRange
 
   template <>
-  std::vector<EventRange> ParameterSet::getParameter<std::vector<EventRange> >(std::string const& name) const;
+  std::vector<EventRange> ParameterSet::getParameter<std::vector<EventRange>>(std::string const& name) const;
 
   // ----------------------------------------------------------------------
   // LuminosityBlockRange
@@ -431,7 +470,7 @@ namespace edm {
   // VLuminosityBlockRange
 
   template <>
-  std::vector<LuminosityBlockRange> ParameterSet::getParameter<std::vector<LuminosityBlockRange> >(
+  std::vector<LuminosityBlockRange> ParameterSet::getParameter<std::vector<LuminosityBlockRange>>(
       std::string const& name) const;
 
   // ----------------------------------------------------------------------
@@ -488,11 +527,11 @@ namespace edm {
   int ParameterSet::getUntrackedParameter<int>(std::string const& name) const;
 
   template <>
-  std::vector<int> ParameterSet::getUntrackedParameter<std::vector<int> >(std::string const& name,
-                                                                          std::vector<int> const& defaultValue) const;
+  std::vector<int> ParameterSet::getUntrackedParameter<std::vector<int>>(std::string const& name,
+                                                                         std::vector<int> const& defaultValue) const;
 
   template <>
-  std::vector<int> ParameterSet::getUntrackedParameter<std::vector<int> >(std::string const& name) const;
+  std::vector<int> ParameterSet::getUntrackedParameter<std::vector<int>>(std::string const& name) const;
 
   // ----------------------------------------------------------------------
   // Uint32, vUint32
@@ -505,11 +544,11 @@ namespace edm {
   unsigned int ParameterSet::getUntrackedParameter<unsigned int>(std::string const& name) const;
 
   template <>
-  std::vector<unsigned int> ParameterSet::getUntrackedParameter<std::vector<unsigned int> >(
+  std::vector<unsigned int> ParameterSet::getUntrackedParameter<std::vector<unsigned int>>(
       std::string const& name, std::vector<unsigned int> const& defaultValue) const;
 
   template <>
-  std::vector<unsigned int> ParameterSet::getUntrackedParameter<std::vector<unsigned int> >(
+  std::vector<unsigned int> ParameterSet::getUntrackedParameter<std::vector<unsigned int>>(
       std::string const& name) const;
 
   // ----------------------------------------------------------------------
@@ -523,11 +562,11 @@ namespace edm {
   unsigned long long ParameterSet::getUntrackedParameter<unsigned long long>(std::string const& name) const;
 
   template <>
-  std::vector<unsigned long long> ParameterSet::getUntrackedParameter<std::vector<unsigned long long> >(
+  std::vector<unsigned long long> ParameterSet::getUntrackedParameter<std::vector<unsigned long long>>(
       std::string const& name, std::vector<unsigned long long> const& defaultValue) const;
 
   template <>
-  std::vector<unsigned long long> ParameterSet::getUntrackedParameter<std::vector<unsigned long long> >(
+  std::vector<unsigned long long> ParameterSet::getUntrackedParameter<std::vector<unsigned long long>>(
       std::string const& name) const;
 
   // ----------------------------------------------------------------------
@@ -541,11 +580,11 @@ namespace edm {
   long long ParameterSet::getUntrackedParameter<long long>(std::string const& name) const;
 
   template <>
-  std::vector<long long> ParameterSet::getUntrackedParameter<std::vector<long long> >(
+  std::vector<long long> ParameterSet::getUntrackedParameter<std::vector<long long>>(
       std::string const& name, std::vector<long long> const& defaultValue) const;
 
   template <>
-  std::vector<long long> ParameterSet::getUntrackedParameter<std::vector<long long> >(std::string const& name) const;
+  std::vector<long long> ParameterSet::getUntrackedParameter<std::vector<long long>>(std::string const& name) const;
 
   // ----------------------------------------------------------------------
   // Double, vDouble
@@ -557,11 +596,11 @@ namespace edm {
   double ParameterSet::getUntrackedParameter<double>(std::string const& name) const;
 
   template <>
-  std::vector<double> ParameterSet::getUntrackedParameter<std::vector<double> >(
+  std::vector<double> ParameterSet::getUntrackedParameter<std::vector<double>>(
       std::string const& name, std::vector<double> const& defaultValue) const;
 
   template <>
-  std::vector<double> ParameterSet::getUntrackedParameter<std::vector<double> >(std::string const& name) const;
+  std::vector<double> ParameterSet::getUntrackedParameter<std::vector<double>>(std::string const& name) const;
 
   // ----------------------------------------------------------------------
   // String, vString
@@ -574,11 +613,11 @@ namespace edm {
   std::string ParameterSet::getUntrackedParameter<std::string>(std::string const& name) const;
 
   template <>
-  std::vector<std::string> ParameterSet::getUntrackedParameter<std::vector<std::string> >(
+  std::vector<std::string> ParameterSet::getUntrackedParameter<std::vector<std::string>>(
       std::string const& name, std::vector<std::string> const& defaultValue) const;
 
   template <>
-  std::vector<std::string> ParameterSet::getUntrackedParameter<std::vector<std::string> >(std::string const& name) const;
+  std::vector<std::string> ParameterSet::getUntrackedParameter<std::vector<std::string>>(std::string const& name) const;
 
   // ----------------------------------------------------------------------
   //  FileInPath
@@ -600,11 +639,11 @@ namespace edm {
   InputTag ParameterSet::getUntrackedParameter<InputTag>(std::string const& name) const;
 
   template <>
-  std::vector<InputTag> ParameterSet::getUntrackedParameter<std::vector<InputTag> >(
+  std::vector<InputTag> ParameterSet::getUntrackedParameter<std::vector<InputTag>>(
       std::string const& name, std::vector<InputTag> const& defaultValue) const;
 
   template <>
-  std::vector<InputTag> ParameterSet::getUntrackedParameter<std::vector<InputTag> >(std::string const& name) const;
+  std::vector<InputTag> ParameterSet::getUntrackedParameter<std::vector<InputTag>>(std::string const& name) const;
 
   // ----------------------------------------------------------------------
   // EventID, VEventID
@@ -616,10 +655,10 @@ namespace edm {
   EventID ParameterSet::getUntrackedParameter<EventID>(std::string const& name) const;
 
   template <>
-  std::vector<EventID> ParameterSet::getUntrackedParameter<std::vector<EventID> >(
+  std::vector<EventID> ParameterSet::getUntrackedParameter<std::vector<EventID>>(
       std::string const& name, std::vector<EventID> const& defaultValue) const;
   template <>
-  std::vector<EventID> ParameterSet::getUntrackedParameter<std::vector<EventID> >(std::string const& name) const;
+  std::vector<EventID> ParameterSet::getUntrackedParameter<std::vector<EventID>>(std::string const& name) const;
 
   // ----------------------------------------------------------------------
   // LuminosityBlockID, VLuminosityBlockID
@@ -632,10 +671,10 @@ namespace edm {
   LuminosityBlockID ParameterSet::getUntrackedParameter<LuminosityBlockID>(std::string const& name) const;
 
   template <>
-  std::vector<LuminosityBlockID> ParameterSet::getUntrackedParameter<std::vector<LuminosityBlockID> >(
+  std::vector<LuminosityBlockID> ParameterSet::getUntrackedParameter<std::vector<LuminosityBlockID>>(
       std::string const& name, std::vector<LuminosityBlockID> const& defaultValue) const;
   template <>
-  std::vector<LuminosityBlockID> ParameterSet::getUntrackedParameter<std::vector<LuminosityBlockID> >(
+  std::vector<LuminosityBlockID> ParameterSet::getUntrackedParameter<std::vector<LuminosityBlockID>>(
       std::string const& name) const;
 
   // ----------------------------------------------------------------------
@@ -649,10 +688,10 @@ namespace edm {
   EventRange ParameterSet::getUntrackedParameter<EventRange>(std::string const& name) const;
 
   template <>
-  std::vector<EventRange> ParameterSet::getUntrackedParameter<std::vector<EventRange> >(
+  std::vector<EventRange> ParameterSet::getUntrackedParameter<std::vector<EventRange>>(
       std::string const& name, std::vector<EventRange> const& defaultValue) const;
   template <>
-  std::vector<EventRange> ParameterSet::getUntrackedParameter<std::vector<EventRange> >(std::string const& name) const;
+  std::vector<EventRange> ParameterSet::getUntrackedParameter<std::vector<EventRange>>(std::string const& name) const;
 
   // ----------------------------------------------------------------------
   // LuminosityBlockRange, VLuminosityBlockRange
@@ -665,10 +704,10 @@ namespace edm {
   LuminosityBlockRange ParameterSet::getUntrackedParameter<LuminosityBlockRange>(std::string const& name) const;
 
   template <>
-  std::vector<LuminosityBlockRange> ParameterSet::getUntrackedParameter<std::vector<LuminosityBlockRange> >(
+  std::vector<LuminosityBlockRange> ParameterSet::getUntrackedParameter<std::vector<LuminosityBlockRange>>(
       std::string const& name, std::vector<LuminosityBlockRange> const& defaultValue) const;
   template <>
-  std::vector<LuminosityBlockRange> ParameterSet::getUntrackedParameter<std::vector<LuminosityBlockRange> >(
+  std::vector<LuminosityBlockRange> ParameterSet::getUntrackedParameter<std::vector<LuminosityBlockRange>>(
       std::string const& name) const;
 
   // specializations
@@ -685,7 +724,7 @@ namespace edm {
   int ParameterSet::getParameter<int>(char const* name) const;
 
   template <>
-  std::vector<int> ParameterSet::getParameter<std::vector<int> >(char const* name) const;
+  std::vector<int> ParameterSet::getParameter<std::vector<int>>(char const* name) const;
 
   // ----------------------------------------------------------------------
   // Int64, vInt64
@@ -694,7 +733,7 @@ namespace edm {
   long long ParameterSet::getParameter<long long>(char const* name) const;
 
   template <>
-  std::vector<long long> ParameterSet::getParameter<std::vector<long long> >(char const* name) const;
+  std::vector<long long> ParameterSet::getParameter<std::vector<long long>>(char const* name) const;
 
   // ----------------------------------------------------------------------
   // Uint32, vUint32
@@ -703,7 +742,7 @@ namespace edm {
   unsigned int ParameterSet::getParameter<unsigned int>(char const* name) const;
 
   template <>
-  std::vector<unsigned int> ParameterSet::getParameter<std::vector<unsigned int> >(char const* name) const;
+  std::vector<unsigned int> ParameterSet::getParameter<std::vector<unsigned int>>(char const* name) const;
 
   // ----------------------------------------------------------------------
   // Uint64, vUint64
@@ -712,7 +751,7 @@ namespace edm {
   unsigned long long ParameterSet::getParameter<unsigned long long>(char const* name) const;
 
   template <>
-  std::vector<unsigned long long> ParameterSet::getParameter<std::vector<unsigned long long> >(char const* name) const;
+  std::vector<unsigned long long> ParameterSet::getParameter<std::vector<unsigned long long>>(char const* name) const;
 
   // ----------------------------------------------------------------------
   // Double, vDouble
@@ -721,7 +760,7 @@ namespace edm {
   double ParameterSet::getParameter<double>(char const* name) const;
 
   template <>
-  std::vector<double> ParameterSet::getParameter<std::vector<double> >(char const* name) const;
+  std::vector<double> ParameterSet::getParameter<std::vector<double>>(char const* name) const;
 
   // ----------------------------------------------------------------------
   // String, vString
@@ -730,7 +769,7 @@ namespace edm {
   std::string ParameterSet::getParameter<std::string>(char const* name) const;
 
   template <>
-  std::vector<std::string> ParameterSet::getParameter<std::vector<std::string> >(char const* name) const;
+  std::vector<std::string> ParameterSet::getParameter<std::vector<std::string>>(char const* name) const;
 
   // ----------------------------------------------------------------------
   // FileInPath
@@ -748,7 +787,19 @@ namespace edm {
   // VInputTag
 
   template <>
-  std::vector<InputTag> ParameterSet::getParameter<std::vector<InputTag> >(char const* name) const;
+  std::vector<InputTag> ParameterSet::getParameter<std::vector<InputTag>>(char const* name) const;
+
+  // ----------------------------------------------------------------------
+  // ESInputTag
+
+  template <>
+  ESInputTag ParameterSet::getParameter<ESInputTag>(char const* name) const;
+
+  // ----------------------------------------------------------------------
+  // VESInputTag
+
+  template <>
+  std::vector<ESInputTag> ParameterSet::getParameter<std::vector<ESInputTag>>(char const* name) const;
 
   // ----------------------------------------------------------------------
   // EventID
@@ -760,7 +811,7 @@ namespace edm {
   // VEventID
 
   template <>
-  std::vector<EventID> ParameterSet::getParameter<std::vector<EventID> >(char const* name) const;
+  std::vector<EventID> ParameterSet::getParameter<std::vector<EventID>>(char const* name) const;
 
   // ----------------------------------------------------------------------
   // LuminosityBlockID
@@ -772,7 +823,7 @@ namespace edm {
   // VLuminosityBlockID
 
   template <>
-  std::vector<LuminosityBlockID> ParameterSet::getParameter<std::vector<LuminosityBlockID> >(char const* name) const;
+  std::vector<LuminosityBlockID> ParameterSet::getParameter<std::vector<LuminosityBlockID>>(char const* name) const;
 
   // ----------------------------------------------------------------------
   // EventRange
@@ -784,7 +835,7 @@ namespace edm {
   // VEventRange
 
   template <>
-  std::vector<EventRange> ParameterSet::getParameter<std::vector<EventRange> >(char const* name) const;
+  std::vector<EventRange> ParameterSet::getParameter<std::vector<EventRange>>(char const* name) const;
 
   // ----------------------------------------------------------------------
   // LuminosityBlockRange
@@ -796,7 +847,7 @@ namespace edm {
   // VLuminosityBlockRange
 
   template <>
-  std::vector<LuminosityBlockRange> ParameterSet::getParameter<std::vector<LuminosityBlockRange> >(
+  std::vector<LuminosityBlockRange> ParameterSet::getParameter<std::vector<LuminosityBlockRange>>(
       char const* name) const;
 
   // ----------------------------------------------------------------------
@@ -829,11 +880,11 @@ namespace edm {
   int ParameterSet::getUntrackedParameter<int>(char const* name) const;
 
   template <>
-  std::vector<int> ParameterSet::getUntrackedParameter<std::vector<int> >(char const* name,
-                                                                          std::vector<int> const& defaultValue) const;
+  std::vector<int> ParameterSet::getUntrackedParameter<std::vector<int>>(char const* name,
+                                                                         std::vector<int> const& defaultValue) const;
 
   template <>
-  std::vector<int> ParameterSet::getUntrackedParameter<std::vector<int> >(char const* name) const;
+  std::vector<int> ParameterSet::getUntrackedParameter<std::vector<int>>(char const* name) const;
 
   // ----------------------------------------------------------------------
   // Uint32, vUint32
@@ -846,11 +897,11 @@ namespace edm {
   unsigned int ParameterSet::getUntrackedParameter<unsigned int>(char const* name) const;
 
   template <>
-  std::vector<unsigned int> ParameterSet::getUntrackedParameter<std::vector<unsigned int> >(
+  std::vector<unsigned int> ParameterSet::getUntrackedParameter<std::vector<unsigned int>>(
       char const* name, std::vector<unsigned int> const& defaultValue) const;
 
   template <>
-  std::vector<unsigned int> ParameterSet::getUntrackedParameter<std::vector<unsigned int> >(char const* name) const;
+  std::vector<unsigned int> ParameterSet::getUntrackedParameter<std::vector<unsigned int>>(char const* name) const;
 
   // ----------------------------------------------------------------------
   // Uint64, vUint64
@@ -863,11 +914,11 @@ namespace edm {
   unsigned long long ParameterSet::getUntrackedParameter<unsigned long long>(char const* name) const;
 
   template <>
-  std::vector<unsigned long long> ParameterSet::getUntrackedParameter<std::vector<unsigned long long> >(
+  std::vector<unsigned long long> ParameterSet::getUntrackedParameter<std::vector<unsigned long long>>(
       char const* name, std::vector<unsigned long long> const& defaultValue) const;
 
   template <>
-  std::vector<unsigned long long> ParameterSet::getUntrackedParameter<std::vector<unsigned long long> >(
+  std::vector<unsigned long long> ParameterSet::getUntrackedParameter<std::vector<unsigned long long>>(
       char const* name) const;
 
   // ----------------------------------------------------------------------
@@ -880,11 +931,11 @@ namespace edm {
   long long ParameterSet::getUntrackedParameter<long long>(char const* name) const;
 
   template <>
-  std::vector<long long> ParameterSet::getUntrackedParameter<std::vector<long long> >(
+  std::vector<long long> ParameterSet::getUntrackedParameter<std::vector<long long>>(
       char const* name, std::vector<long long> const& defaultValue) const;
 
   template <>
-  std::vector<long long> ParameterSet::getUntrackedParameter<std::vector<long long> >(char const* name) const;
+  std::vector<long long> ParameterSet::getUntrackedParameter<std::vector<long long>>(char const* name) const;
 
   // ----------------------------------------------------------------------
   // Double, vDouble
@@ -896,11 +947,11 @@ namespace edm {
   double ParameterSet::getUntrackedParameter<double>(char const* name) const;
 
   template <>
-  std::vector<double> ParameterSet::getUntrackedParameter<std::vector<double> >(
+  std::vector<double> ParameterSet::getUntrackedParameter<std::vector<double>>(
       char const* name, std::vector<double> const& defaultValue) const;
 
   template <>
-  std::vector<double> ParameterSet::getUntrackedParameter<std::vector<double> >(char const* name) const;
+  std::vector<double> ParameterSet::getUntrackedParameter<std::vector<double>>(char const* name) const;
 
   // ----------------------------------------------------------------------
   // String, vString
@@ -912,11 +963,11 @@ namespace edm {
   std::string ParameterSet::getUntrackedParameter<std::string>(char const* name) const;
 
   template <>
-  std::vector<std::string> ParameterSet::getUntrackedParameter<std::vector<std::string> >(
+  std::vector<std::string> ParameterSet::getUntrackedParameter<std::vector<std::string>>(
       char const* name, std::vector<std::string> const& defaultValue) const;
 
   template <>
-  std::vector<std::string> ParameterSet::getUntrackedParameter<std::vector<std::string> >(char const* name) const;
+  std::vector<std::string> ParameterSet::getUntrackedParameter<std::vector<std::string>>(char const* name) const;
 
   // ----------------------------------------------------------------------
   //  FileInPath
@@ -937,11 +988,11 @@ namespace edm {
   InputTag ParameterSet::getUntrackedParameter<InputTag>(char const* name) const;
 
   template <>
-  std::vector<InputTag> ParameterSet::getUntrackedParameter<std::vector<InputTag> >(
+  std::vector<InputTag> ParameterSet::getUntrackedParameter<std::vector<InputTag>>(
       char const* name, std::vector<InputTag> const& defaultValue) const;
 
   template <>
-  std::vector<InputTag> ParameterSet::getUntrackedParameter<std::vector<InputTag> >(char const* name) const;
+  std::vector<InputTag> ParameterSet::getUntrackedParameter<std::vector<InputTag>>(char const* name) const;
 
   // ----------------------------------------------------------------------
   // EventID, VEventID
@@ -953,10 +1004,10 @@ namespace edm {
   EventID ParameterSet::getUntrackedParameter<EventID>(char const* name) const;
 
   template <>
-  std::vector<EventID> ParameterSet::getUntrackedParameter<std::vector<EventID> >(
+  std::vector<EventID> ParameterSet::getUntrackedParameter<std::vector<EventID>>(
       char const* name, std::vector<EventID> const& defaultValue) const;
   template <>
-  std::vector<EventID> ParameterSet::getUntrackedParameter<std::vector<EventID> >(char const* name) const;
+  std::vector<EventID> ParameterSet::getUntrackedParameter<std::vector<EventID>>(char const* name) const;
 
   // ----------------------------------------------------------------------
   // LuminosityBlockID, VLuminosityBlockID
@@ -969,10 +1020,10 @@ namespace edm {
   LuminosityBlockID ParameterSet::getUntrackedParameter<LuminosityBlockID>(char const* name) const;
 
   template <>
-  std::vector<LuminosityBlockID> ParameterSet::getUntrackedParameter<std::vector<LuminosityBlockID> >(
+  std::vector<LuminosityBlockID> ParameterSet::getUntrackedParameter<std::vector<LuminosityBlockID>>(
       char const* name, std::vector<LuminosityBlockID> const& defaultValue) const;
   template <>
-  std::vector<LuminosityBlockID> ParameterSet::getUntrackedParameter<std::vector<LuminosityBlockID> >(
+  std::vector<LuminosityBlockID> ParameterSet::getUntrackedParameter<std::vector<LuminosityBlockID>>(
       char const* name) const;
 
   // ----------------------------------------------------------------------
@@ -985,10 +1036,10 @@ namespace edm {
   EventRange ParameterSet::getUntrackedParameter<EventRange>(char const* name) const;
 
   template <>
-  std::vector<EventRange> ParameterSet::getUntrackedParameter<std::vector<EventRange> >(
+  std::vector<EventRange> ParameterSet::getUntrackedParameter<std::vector<EventRange>>(
       char const* name, std::vector<EventRange> const& defaultValue) const;
   template <>
-  std::vector<EventRange> ParameterSet::getUntrackedParameter<std::vector<EventRange> >(char const* name) const;
+  std::vector<EventRange> ParameterSet::getUntrackedParameter<std::vector<EventRange>>(char const* name) const;
 
   // ----------------------------------------------------------------------
   // LuminosityBlockRange, VLuminosityBlockRange
@@ -1001,10 +1052,10 @@ namespace edm {
   LuminosityBlockRange ParameterSet::getUntrackedParameter<LuminosityBlockRange>(char const* name) const;
 
   template <>
-  std::vector<LuminosityBlockRange> ParameterSet::getUntrackedParameter<std::vector<LuminosityBlockRange> >(
+  std::vector<LuminosityBlockRange> ParameterSet::getUntrackedParameter<std::vector<LuminosityBlockRange>>(
       char const* name, std::vector<LuminosityBlockRange> const& defaultValue) const;
   template <>
-  std::vector<LuminosityBlockRange> ParameterSet::getUntrackedParameter<std::vector<LuminosityBlockRange> >(
+  std::vector<LuminosityBlockRange> ParameterSet::getUntrackedParameter<std::vector<LuminosityBlockRange>>(
       char const* name) const;
 
   // ----------------------------------------------------------------------
diff --git a/FWCore/ParameterSet/interface/getFixedSizeArray.h b/FWCore/ParameterSet/interface/getFixedSizeArray.h
deleted file mode 100644
index aee4f7a92d81d..0000000000000
--- a/FWCore/ParameterSet/interface/getFixedSizeArray.h
+++ /dev/null
@@ -1,28 +0,0 @@
-#ifndef FWCore_ParameterSet_getFixedSizeArray_h
-#define FWCore_ParameterSet_getFixedSizeArray_h
-
-#include "FWCore/ParameterSet/interface/ParameterSet.h"
-#include "FWCore/Utilities/interface/EDMException.h"
-
-#include <algorithm>
-#include <array>
-#include <cstddef>
-#include <string>
-#include <vector>
-
-namespace edm {
-
-  template <class T, std::size_t N>
-  std::array<T, N> getFixedSizeArray(ParameterSet const& pset, std::string const& name) {
-    std::vector<T> vec = pset.getParameter<std::vector<T>>(name);
-    if (vec.size() != N) {
-      throw Exception(errors::Configuration)
-          << "The parameter '" << name << "' should have " << N << " elements, but has " << vec.size()
-          << " elements in the configuration.\n";
-    }
-    std::array<T, N> a{};
-    std::copy_n(vec.begin(), N, a.begin());
-    return a;
-  }
-}  // namespace edm
-#endif
diff --git a/FWCore/ParameterSet/src/ANDGroupDescription.cc b/FWCore/ParameterSet/src/ANDGroupDescription.cc
index fb27d84d93518..a8f7c9ff313f2 100644
--- a/FWCore/ParameterSet/src/ANDGroupDescription.cc
+++ b/FWCore/ParameterSet/src/ANDGroupDescription.cc
@@ -1,5 +1,5 @@
 
-#include "FWCore/ParameterSet/interface/ANDGroupDescription.h"
+#include "FWCore/ParameterSet/src/ANDGroupDescription.h"
 #include "FWCore/Utilities/interface/EDMException.h"
 #include "FWCore/ParameterSet/interface/DocFormatHelper.h"
 
diff --git a/FWCore/ParameterSet/interface/ANDGroupDescription.h b/FWCore/ParameterSet/src/ANDGroupDescription.h
similarity index 100%
rename from FWCore/ParameterSet/interface/ANDGroupDescription.h
rename to FWCore/ParameterSet/src/ANDGroupDescription.h
diff --git a/FWCore/ParameterSet/src/FillDescriptionFromPSet.cc b/FWCore/ParameterSet/src/FillDescriptionFromPSet.cc
index e359aef0893a8..f31c34e56632a 100644
--- a/FWCore/ParameterSet/src/FillDescriptionFromPSet.cc
+++ b/FWCore/ParameterSet/src/FillDescriptionFromPSet.cc
@@ -1,5 +1,5 @@
 
-#include "FWCore/ParameterSet/interface/FillDescriptionFromPSet.h"
+#include "FWCore/ParameterSet/src/FillDescriptionFromPSet.h"
 #include "FWCore/ParameterSet/interface/ParameterDescriptionNode.h"
 #include "FWCore/ParameterSet/interface/ParameterSetDescription.h"
 #include "FWCore/ParameterSet/interface/ParameterSet.h"
diff --git a/FWCore/ParameterSet/interface/FillDescriptionFromPSet.h b/FWCore/ParameterSet/src/FillDescriptionFromPSet.h
similarity index 100%
rename from FWCore/ParameterSet/interface/FillDescriptionFromPSet.h
rename to FWCore/ParameterSet/src/FillDescriptionFromPSet.h
diff --git a/FWCore/ParameterSet/src/ORGroupDescription.cc b/FWCore/ParameterSet/src/ORGroupDescription.cc
index f394780600d10..64f5d8e4f3cf8 100644
--- a/FWCore/ParameterSet/src/ORGroupDescription.cc
+++ b/FWCore/ParameterSet/src/ORGroupDescription.cc
@@ -1,5 +1,5 @@
 
-#include "FWCore/ParameterSet/interface/ORGroupDescription.h"
+#include "FWCore/ParameterSet/src/ORGroupDescription.h"
 #include "FWCore/Utilities/interface/EDMException.h"
 #include "FWCore/ParameterSet/interface/DocFormatHelper.h"
 
diff --git a/FWCore/ParameterSet/interface/ORGroupDescription.h b/FWCore/ParameterSet/src/ORGroupDescription.h
similarity index 100%
rename from FWCore/ParameterSet/interface/ORGroupDescription.h
rename to FWCore/ParameterSet/src/ORGroupDescription.h
diff --git a/FWCore/ParameterSet/src/ParameterDescription.cc b/FWCore/ParameterSet/src/ParameterDescription.cc
index 7bda236813c23..efdca7d9aa044 100644
--- a/FWCore/ParameterSet/src/ParameterDescription.cc
+++ b/FWCore/ParameterSet/src/ParameterDescription.cc
@@ -7,7 +7,7 @@
 #include "DataFormats/Provenance/interface/LuminosityBlockRange.h"
 #include "FWCore/ParameterSet/interface/DocFormatHelper.h"
 #include "FWCore/ParameterSet/interface/FileInPath.h"
-#include "FWCore/ParameterSet/interface/FillDescriptionFromPSet.h"
+#include "FWCore/ParameterSet/src/FillDescriptionFromPSet.h"
 #include "FWCore/ParameterSet/interface/ParameterSetDescription.h"
 #include "FWCore/ParameterSet/interface/VParameterSetEntry.h"
 #include "FWCore/Utilities/interface/Algorithms.h"
diff --git a/FWCore/ParameterSet/src/ParameterDescriptionNode.cc b/FWCore/ParameterSet/src/ParameterDescriptionNode.cc
index 1fa1a6bf2edf1..06821aa0a25c8 100644
--- a/FWCore/ParameterSet/src/ParameterDescriptionNode.cc
+++ b/FWCore/ParameterSet/src/ParameterDescriptionNode.cc
@@ -1,9 +1,9 @@
 
 #include "FWCore/ParameterSet/interface/ParameterDescriptionNode.h"
 #include "FWCore/ParameterSet/interface/ParameterDescriptionCases.h"
-#include "FWCore/ParameterSet/interface/ANDGroupDescription.h"
-#include "FWCore/ParameterSet/interface/ORGroupDescription.h"
-#include "FWCore/ParameterSet/interface/XORGroupDescription.h"
+#include "FWCore/ParameterSet/src/ANDGroupDescription.h"
+#include "FWCore/ParameterSet/src/ORGroupDescription.h"
+#include "FWCore/ParameterSet/src/XORGroupDescription.h"
 #include "FWCore/ParameterSet/interface/DocFormatHelper.h"
 
 #include <vector>
diff --git a/FWCore/ParameterSet/src/ParameterSet.cc b/FWCore/ParameterSet/src/ParameterSet.cc
index 7bf4828858c49..d22f363866c40 100644
--- a/FWCore/ParameterSet/src/ParameterSet.cc
+++ b/FWCore/ParameterSet/src/ParameterSet.cc
@@ -11,7 +11,7 @@
 
 #include "FWCore/MessageLogger/interface/MessageLogger.h"
 #include "FWCore/ParameterSet/interface/Registry.h"
-#include "FWCore/ParameterSet/interface/split.h"
+#include "FWCore/ParameterSet/src/split.h"
 #include "FWCore/Utilities/interface/Algorithms.h"
 #include "FWCore/Utilities/interface/Digest.h"
 #include "FWCore/Utilities/interface/EDMException.h"
@@ -29,6 +29,13 @@
 
 namespace edm {
 
+  namespace pset::exceptions {
+    void throwWrongNumberOfElements(std::string const& iName, size_t iExpected, size_t iGot) {
+      throw Exception(errors::Configuration) << "The parameter '" << iName << "' should have " << iExpected
+                                             << " elements, but has " << iGot << " elements in the configuration.\n";
+    }
+  }  // namespace pset::exceptions
+
   void ParameterSet::invalidateRegistration(std::string const& nameOfTracked) {
     // We have added a new parameter.  Invalidate the ID.
     if (isRegistered()) {
diff --git a/FWCore/ParameterSet/src/ParameterSetConverter.cc b/FWCore/ParameterSet/src/ParameterSetConverter.cc
index 5b23740ab53da..be0ed675ac1d1 100644
--- a/FWCore/ParameterSet/src/ParameterSetConverter.cc
+++ b/FWCore/ParameterSet/src/ParameterSetConverter.cc
@@ -10,7 +10,7 @@ ParameterSetConverter.cc
 #include "FWCore/ParameterSet/interface/ParameterSetConverter.h"
 #include <iterator>
 #include "FWCore/ParameterSet/interface/Registry.h"
-#include "FWCore/ParameterSet/interface/split.h"
+#include "FWCore/ParameterSet/src/split.h"
 #include "FWCore/Utilities/interface/Algorithms.h"
 
 namespace edm {
diff --git a/FWCore/ParameterSet/src/VParameterSetEntry.cc b/FWCore/ParameterSet/src/VParameterSetEntry.cc
index cb9fff8537642..79fdc007cbcaf 100644
--- a/FWCore/ParameterSet/src/VParameterSetEntry.cc
+++ b/FWCore/ParameterSet/src/VParameterSetEntry.cc
@@ -1,6 +1,6 @@
 #include "FWCore/ParameterSet/interface/VParameterSetEntry.h"
 #include "FWCore/ParameterSet/interface/ParameterSet.h"
-#include "FWCore/ParameterSet/interface/split.h"
+#include "FWCore/ParameterSet/src/split.h"
 #include "FWCore/Utilities/interface/Digest.h"
 
 #include <cassert>
diff --git a/FWCore/ParameterSet/src/XORGroupDescription.cc b/FWCore/ParameterSet/src/XORGroupDescription.cc
index 9e278e3f49329..76b915c0e12b6 100644
--- a/FWCore/ParameterSet/src/XORGroupDescription.cc
+++ b/FWCore/ParameterSet/src/XORGroupDescription.cc
@@ -1,5 +1,5 @@
 
-#include "FWCore/ParameterSet/interface/XORGroupDescription.h"
+#include "FWCore/ParameterSet/src/XORGroupDescription.h"
 #include "FWCore/Utilities/interface/EDMException.h"
 #include "FWCore/ParameterSet/interface/DocFormatHelper.h"
 
diff --git a/FWCore/ParameterSet/interface/XORGroupDescription.h b/FWCore/ParameterSet/src/XORGroupDescription.h
similarity index 100%
rename from FWCore/ParameterSet/interface/XORGroupDescription.h
rename to FWCore/ParameterSet/src/XORGroupDescription.h
diff --git a/FWCore/ParameterSet/interface/split.h b/FWCore/ParameterSet/src/split.h
similarity index 100%
rename from FWCore/ParameterSet/interface/split.h
rename to FWCore/ParameterSet/src/split.h
diff --git a/FWCore/ParameterSet/src/types.cc b/FWCore/ParameterSet/src/types.cc
index 57121cda9ad32..d5b81cf890cec 100644
--- a/FWCore/ParameterSet/src/types.cc
+++ b/FWCore/ParameterSet/src/types.cc
@@ -9,7 +9,7 @@
 #include "FWCore/ParameterSet/interface/types.h"
 
 #include "boost/lexical_cast.hpp"
-#include "FWCore/ParameterSet/interface/split.h"
+#include "FWCore/ParameterSet/src/split.h"
 #include "FWCore/Utilities/interface/Parse.h"
 #include <cctype>
 #include <cstdlib>