code: public static <T extends CharSequence> T checkNotEmpty(final T reference) {
          if (TextUtils.isEmpty(reference)) {
              throw new IllegalArgumentException();
          }
          return reference;
      }
docs: Ensures that a CharSequence passed as a parameter to the calling method is
  not null and not empty.
  
  @param reference an CharSequence reference
  @return the non-empty reference that was validated
  @throws IllegalArgumentException if {@code reference} was null or empty