False Positive - Tests should include assertions - S2699

We have a lots of code (not all) on which an issue gets reported for not having an assert but it does exist in the test method.

Example Code that gets the violation:

@Test
public void successfullValidation() throws ErrorInfo_Exception {
   AgencyInfoServiceResponse agencyResponse = new AgencyInfoServiceResponse();
   AgencyInfoServiceResponseHeader header = new AgencyInfoServiceResponseHeader();
   header.setCmdStatus("Success");
   header.setCmdType("response");
   agencyResponse.setAgencyInfoServiceResponseHeader(header);
   assertTrue(validator.validate(agencyResponse));
}

But if I pull out the validator into a variable and assertTrue the variable then the violation goes away. The assertTrue import is: import static org.junit.Assert.assertTrue;

I am using SonarQube 6.4.0.25310 with SonarJava 4.10.0.10260.

Why is it saying I do not have an assert?