[attribute][complex] extend to java.util.Map

Add `java.util.Map` to the list of supported `JMXComplexAttribute`
types.

Author: yannmh

src/main/java/org/datadog/jmxfetch/Instance.java

@@ -25,7 +25,7 @@ public class Instance {
             "java.lang.String", "int", "float", "double", "java.lang.Double","java.lang.Float", "java.lang.Integer", "java.lang.Long",
             "java.util.concurrent.atomic.AtomicInteger", "java.util.concurrent.atomic.AtomicLong",
             "java.lang.Object", "java.lang.Boolean", "boolean", "java.lang.Number");
-    private final static List<String> COMPOSED_TYPES = Arrays.asList("javax.management.openmbean.CompositeData", "java.util.HashMap");
+    private final static List<String> COMPOSED_TYPES = Arrays.asList("javax.management.openmbean.CompositeData", "java.util.HashMap", "java.util.Map");
     private final static int MAX_RETURNED_METRICS = 350;
     private final static int DEFAULT_REFRESH_BEANS_PERIOD = 600;
     public static final String PROCESS_NAME_REGEX = "process_name_regex";