code: public static void notNull(final Object object, final String argumentName) {
          if (object == null) {
              throw new NullPointerException(getMessage("null", argumentName));
          }
      }
docs: Validates that the supplied object is not null, and throws a NullPointerException otherwise.
  
  @param object       The object to validate for {@code null}-ness.
  @param argumentName The argument name of the object to validate. If supplied (i.e. non-{@code null}),
  this value is used in composing a better exception message.