code: public static String hasText(String value, String message) {
  		if (value == null) {
  			throw new IllegalArgumentException(message);
  		}
  
  		for (char c : value.toCharArray()) {
  			if (!Character.isWhitespace(c)) {
  				return value;
  			}
  		}
  
  		// Found only whitespace characters...
  		throw new IllegalArgumentException(message);
  	}
docs: Check that a given string value is not blank (i.e. not null,
  not empty and does not contain only whitespaces).
  If value is blank, an {@link java.lang.IllegalArgumentException} is
  thrown.
  If value is not blank, original string value is automatically returned.
  
  @param value String value.
  @param message Error message given to exception.
  @return Original string value.
  @throws java.lang.IllegalArgumentException if value is blank.