[ARROW-6738][Java] Rule out the change for union type comparison

Author: liyafan82

java/vector/src/main/java/org/apache/arrow/vector/compare/RangeEqualsVisitor.java

@@ -217,7 +217,9 @@ protected boolean compareUnionVectors(Range range) {
           return false;
         }
       }
-      RangeEqualsVisitor visitor = createInnerVisitor(leftSubVector, rightSubVector, true);
+      TypeEqualsVisitor typeVisitor = new TypeEqualsVisitor(rightSubVector);
+      RangeEqualsVisitor visitor =
+          createInnerVisitor(leftSubVector, rightSubVector, (left, right) -> typeVisitor.equals(left));
       if (!visitor.rangeEquals(subRange)) {
         return false;
       }

java/vector/src/test/java/org/apache/arrow/vector/compare/TestRangeEqualsVisitor.java

@@ -309,8 +309,8 @@ public void testUnionVectorSubRangeEquals() {
       vector1.setSafe(2, intHolder);
       vector1.setValueCount(3);
 
-      vector2.setType(0, Types.MinorType.SMALLINT);
-      vector2.setSafe(0, intHolder);
+      vector2.setType(0, Types.MinorType.UINT4);
+      vector2.setSafe(0, uInt4Holder);
 
       vector2.setType(1, Types.MinorType.INT);
       vector2.setSafe(1, intHolder);