replace string.Join+empty with sting.concat

src/Humanizer/Localisation/NumberToWords/CroatianNumberToWordsConverter.cs

@@ -94,7 +94,7 @@ public override string Convert(long input)
                 }
             }
 
-            return string.Join("", parts);
+            return string.Concat(parts);
         }
 
         public override string ConvertToOrdinal(int number) =>

src/Humanizer/Localisation/NumberToWords/FinnishNumberToWordsConverter.cs

@@ -82,7 +82,7 @@ public override string Convert(long input)
                 parts.Add(UnitsMap[number]);
             }
 
-            return string.Join("", parts).Trim();
+            return string.Concat( parts).Trim();
         }
 
         static string GetOrdinalUnit(int number, bool useExceptions)
@@ -143,7 +143,7 @@ static string ToOrdinal(int number, bool useExceptions)
                 parts.Add(GetOrdinalUnit(number, useExceptions));
             }
 
-            return string.Join("", parts);
+            return string.Concat(parts);
         }
 
         public override string ConvertToOrdinal(int number) =>

src/Humanizer/Localisation/NumberToWords/GermanNumberToWordsConverterBase.cs

@@ -61,7 +61,7 @@ public override string Convert(long number, GrammaticalGender gender, bool addAn
                 }
             }
 
-            return string.Join("", parts);
+            return string.Concat(parts);
         }
 
         public override string ConvertToOrdinal(int number, GrammaticalGender gender)
@@ -95,7 +95,7 @@ public override string ConvertToOrdinal(int number, GrammaticalGender gender)
 
             parts.Add(GetEndingForGender(gender));
 
-            return string.Join("", parts);
+            return string.Concat(parts);
         }
 
         void CollectParts(ICollection<string> parts, ref long number, long divisor, bool addSpaceBeforeNextPart, string pluralFormat, string singular)

src/Humanizer/Localisation/NumberToWords/LuxembourgishNumberToWordsConverter.cs

@@ -41,7 +41,7 @@ public override string Convert(long number, WordForm wordForm, GrammaticalGender
 
         if (number <= 0)
         {
-            return string.Join("", parts);
+            return string.Concat(parts);
         }
 
         if (number < 20)
@@ -78,7 +78,7 @@ public override string Convert(long number, WordForm wordForm, GrammaticalGender
             parts.Add(tens);
         }
 
-        return string.Join("", parts);
+        return string.Concat(parts);
     }
 
     public override string ConvertToOrdinal(int number, GrammaticalGender gender)
@@ -112,7 +112,7 @@ public override string ConvertToOrdinal(int number, GrammaticalGender gender)
 
         parts.Add(GetEndingForGender(gender));
 
-        return string.Join("", parts);
+        return string.Concat(parts);
     }
 
     private void CollectParts(ICollection<string> parts, ref long number, long divisor, bool addSpaceBeforeNextPart, string pluralFormat, string singular)

src/Humanizer/Localisation/NumberToWords/RussianNumberToWordsConverter.cs

@@ -164,7 +164,7 @@ static string GetPrefix(long number)
                 parts.Add(number == 1 ? "одно" : UnitsOrdinalPrefixes[number]);
             }
 
-            return string.Join("", parts);
+            return string.Concat(parts);
         }
 
         static void CollectParts(ICollection<string> parts, ref long number, long divisor, GrammaticalGender gender, params string[] forms)

src/Humanizer/Localisation/NumberToWords/SerbianCyrlNumberToWordsConverter.cs

@@ -96,7 +96,7 @@ public override string Convert(long input)
                 }
             }
 
-            return string.Join("", parts);
+            return string.Concat(parts);
         }
 
         public override string ConvertToOrdinal(int number) =>

src/Humanizer/Localisation/NumberToWords/SerbianNumberToWordsConverter.cs

@@ -94,7 +94,7 @@ public override string Convert(long input)
                 }
             }
 
-            return string.Join("", parts);
+            return string.Concat(parts);
         }
 
         public override string ConvertToOrdinal(int number) =>

src/Humanizer/Localisation/NumberToWords/SlovenianNumberToWordsConverter.cs

@@ -94,7 +94,7 @@ public override string Convert(long input)
                 }
             }
 
-            return string.Join("", parts);
+            return string.Concat(parts);
         }
 
         public override string ConvertToOrdinal(int number) =>

src/Humanizer/Localisation/NumberToWords/UkrainianNumberToWordsConverter.cs

@@ -163,7 +163,7 @@ static string GetPrefix(int number)
                 parts.Add(number == 1 ? "одно" : UnitsOrdinalPrefixes[number]);
             }
 
-            return string.Join("", parts);
+            return string.Concat(parts);
         }
 
         static void CollectParts(ICollection<string> parts, ref long number, long divisor, GrammaticalGender gender, params string[] forms)

src/Humanizer/StringDehumanizeExtensions.cs

@@ -13,7 +13,7 @@ public static class StringDehumanizeExtensions
         public static string Dehumanize(this string input)
         {
             var pascalizedWords = input.Split(' ').Select(word => word.Humanize().Pascalize());
-            return string.Join("", pascalizedWords).Replace(" ", "");
+            return string.Concat(pascalizedWords).Replace(" ", "");
         }
     }
 }