public ShenYuTestCaseSpecBuilder addNotExists(final Method method, final String endpoint) {
            return add(notExists(method, endpoint));
        }
add not exists case spec.
@param method method
@param endpoint endpoint
@return ShenYuTestCaseSpecBuilder
shenyu-e2e/shenyu-e2e-engine/src/main/java/org/apache/shenyu/e2e/engine/scenario/specification/ShenYuCaseSpec.java