private void assertNoPayload(RestTest restTest, Response response) {
        String expectedPayload = restTest.getExpectedResponsePayload();
        if (expectedPayload != null && expectedPayload.trim().length() > 0) {
            Assert.fail("Expected a payload but didn't get one.");
        }
    }
Asserts that the response has no payload and that we are not expecting one.

@param restTest
@param response
test/common/src/main/java/io/apiman/test/common/util/TestPlanRunner.java