code: public static void hasText(String text, String message) {
          if (!Strings.hasText(text)) {
              throw new IllegalArgumentException(message);
          }
      }
docs: Assert that the given String has valid text content; that is, it must not
  be <code>null</code> and must contain at least one non-whitespace character.
  <pre class="code">Assert.hasText(name, "'name' must not be empty");</pre>
  @param text the String to check
  @param message the exception message to use if the assertion fails
  @see Strings#hasText