implement hashCode and equals in JwtMap

src/main/java/io/jsonwebtoken/impl/JwtMap.java

@@ -155,4 +155,16 @@ public class JwtMap implements Map<String,Object> {
     public String toString() {
         return map.toString();
     }
+
+    @Override
+    public int hashCode()
+    {
+        return map.hashCode();
+    }
+
+    @Override
+    public boolean equals(Object obj)
+    {
+        return map.equals(obj);
+    }
 }

src/test/java/io.jsonwebtoken.impl/JavaJwtMapTest.java

@@ -0,0 +1,39 @@
+package io.jsonwebtoken.impl;
+
+import org.junit.Test;
+
+import static junit.framework.Assert.assertTrue;
+import static junit.framework.TestCase.assertEquals;
+
+/**
+ * Java specific test to ensure we don't hit Groovy's DefaultGroovyMethods
+ */
+public class JavaJwtMapTest
+{
+
+  @Test
+  public void testEquals() throws Exception
+  {
+    JwtMap jwtMap1 = new JwtMap();
+    jwtMap1.put("a", "a");
+
+    JwtMap jwtMap2 = new JwtMap();
+    jwtMap2.put("a", "a");
+
+    assertEquals(jwtMap1, jwtMap2);
+  }
+
+  @Test
+  public void testHashCode() throws Exception
+  {
+    JwtMap jwtMap = new JwtMap();
+    int hashCodeEmpty = jwtMap.hashCode();
+
+    jwtMap.put("a", "b");
+    int hashCodeNonEmpty = jwtMap.hashCode();
+    assertTrue(hashCodeEmpty != hashCodeNonEmpty);
+
+    int identityHash = System.identityHashCode(jwtMap);
+    assertTrue(hashCodeNonEmpty != identityHash);
+  }
+}