code: public <T1 extends Throwable, T2 extends Throwable> 
                  RuntimeException throwIf(Class<T1> t1, Class<T2> t2) 
                  throws T1, T2 {
          return throwIf(t1, t2, NULL_EX, NULL_EX);
      }
docs: Throws the {@linkplain #getResolvingCause() cause} if it is one of the
  specified types, otherwise returns a
  {@linkplain #asRuntimeException() runtime exception}.
  @param <T1>
  @param <T2>
  @param t1
  @param t2
  @return runtime exception
  @throws T1
  @throws T2