@VisibleForTesting
  boolean indexCannotBeUsed(ExecutionContext context, IndexData indexData) {
    if (indexData == null) {
      return false;
    }
    if (!(indexData.getIndex() instanceof AbstractMapIndex)) {
      return false;
    }
    if (!(((AbstractMapIndex) indexData.getIndex()).getIsAllKeys())) {
      return false;
    }
    if (_operator == TOK_NE) {
      return true;
    }
    try {
      if (_right != null
          && (_right instanceof CompiledLiteral)
          && _right.evaluate(context) == null) {
        return true;
      }
      if (_left != null
          && (_left instanceof CompiledLiteral)
          && _left.evaluate(context) == null) {
        return true;
      }
    } catch (Exception e) {
      return false;
    }
    return false;
  }
@return true if the index is a MapIndex of type allkeys ([*]) and this is a != comparison
        or it is comparing the map value against null
geode-core/src/main/java/org/apache/geode/cache/query/internal/CompiledComparison.java