@Test
  public void testSimplePredicate() throws Exception {
    SimpleValidationResult result = catalog.validateSimplePredicate("${body} == 'abc'");
    assertTrue(result.isSuccess());
    assertEquals("${body} == 'abc'", result.getSimple());

    result = catalog.validateSimplePredicate("${body} > ${header.size");
    assertFalse(result.isSuccess());
    assertEquals("${body} > ${header.size", result.getSimple());
    LOG.info(result.getError());
    assertTrue(
        result.getError().startsWith("expected symbol functionEnd but was eol at location 22"));
  }
  @Test
  public void testSimpleExpression() throws Exception {
    SimpleValidationResult result = catalog.validateSimpleExpression("${body}");
    assertTrue(result.isSuccess());
    assertEquals("${body}", result.getSimple());

    result = catalog.validateSimpleExpression("${body");
    assertFalse(result.isSuccess());
    assertEquals("${body", result.getSimple());
    LOG.info(result.getError());
    assertTrue(
        result.getError().startsWith("expected symbol functionEnd but was eol at location 5"));
  }