@Test
 public void testCreateQuotedConstantNumber() throws Exception {
   assertEquals("-123", StringUtils.createQuotedConstant("-123"));
 }
 @Test
 public void testCreateQuotedConstant() throws Exception {
   assertEquals("\" abc \"", StringUtils.createQuotedConstant(" abc "));
 }
 @Test
 public void testCreateQuotedConstantNull() throws Exception {
   assertNull(StringUtils.createQuotedConstant(null));
 }