Fix inconsistent equals and hashcode when annotations are cleared

src/com/amazon/ion/impl/lite/IonValueLite.java

@@ -983,18 +983,18 @@ public final int findTypeAnnotation(String annotation)
     protected int hashTypeAnnotations(final int original)
     {
         final SymbolToken[] tokens = _annotations == null ? SymbolToken.EMPTY_ARRAY : _annotations;
-        if (tokens.length == 0)
-        {
-            return original;
-        }
-
         // Note: Because the tokens array doubles in size when it grows, tokens.length does not correctly convey
         // the actual number of annotations on the value.
         int count = 0;
         while (count < tokens.length && tokens[count] != null) {
             count++;
         }
 
+        if (count == 0)
+        {
+            return original;
+        }
+
         int result = valueHashSalt * original + count;
 
         for (int i = 0; i < count; i++)

test/com/amazon/ion/IonValueTest.java

@@ -197,6 +197,8 @@ public void testClearTypeAnnotations() {
         IonValue v = system().singleValue("a::b::null");
         v.clearTypeAnnotations();
         assertAnnotations(v);
+
+        IonAssert.assertIonEquals(system().newNull(), v);
     }
 
     @Test
@@ -252,16 +254,20 @@ public void testRemoveTypeAnnotation()
 
         v.removeTypeAnnotation(ann);
         assertAnnotations(v);
+        IonAssert.assertIonEquals(system().newNull(), v);
 
         v = system().singleValue("ann::ben::cam::null");
         v.removeTypeAnnotation(ben);
         assertAnnotations(v, ann, "cam");
+        IonAssert.assertIonEquals(system().singleValue("ann::cam::null"), v);
         v.removeTypeAnnotation(ben);
         assertAnnotations(v, ann, "cam");
         v.removeTypeAnnotation("cam");
         assertAnnotations(v, ann);
+        IonAssert.assertIonEquals(system().singleValue("ann::null"), v);
         v.removeTypeAnnotation(ann);
         assertAnnotations(v);
+        IonAssert.assertIonEquals(system().newNull(), v);
     }
 
     @Test

test/com/amazon/ion/junit/IonAssert.java

@@ -330,7 +330,12 @@ private static void doAssertIonEquals(String path,
                                           IonValue expected,
                                           IonValue actual)
     {
-        if (expected == actual) return;
+        if (expected == actual) {
+            if (expected != null) {
+                assertEquals("IonValues were equal, but have unequal hash codes.", expected.hashCode(), actual.hashCode());
+            }
+            return;
+        }
 
         IonType expectedType = expected.getType();
         assertSame(path + " type", expectedType, actual.getType());