private void putCompressedString(Region<Object, Object> region, List<ExpectedValues> expected)
      throws IOException {
    String key = "keyString";
    String value = "this is a string";
    region.put(key, value);
    HeapDataOutputStream hdos = new HeapDataOutputStream(KnownVersion.CURRENT);
    DataSerializer.writeObject(value, hdos);
    byte[] uncompressedBytes = hdos.toByteArray();
    byte[] expectedValue = SnappyCompressor.getDefaultInstance().compress(uncompressedBytes);
    expected.add(
        new ExpectedValues(expectedValue, 32, "compressed object of size " + expectedValue.length,
            -1, getMemoryAddress(region, key), 1, 0, true, true));
  }
Returns -1 if m1 is missing a key in m2, 1 if m2 is missing a key in m1, or 0 is they contain
the exact same keys.

@throws NullPointerException if either c1 or c2 is null
geode-core/src/integrationTest/java/org/apache/geode/internal/offheap/OffHeapValidationJUnitTest.java