code: public <T1 extends Throwable> 
                  RuntimeException throwIf(Class<T1> t1) 
                  throws T1 {
          return throwIf(t1, NULL_EX, NULL_EX, NULL_EX);
      }
docs: Throws the {@linkplain #getResolvingCause() cause} if it is the
  specified type, otherwise returns a
  {@linkplain #asRuntimeException() runtime exception}.
  @param <T1>
  @param t1
  @return runtime exception
  @throws T1