ImmutableJsonString extends AbstractJsonValue { public static ImmutableJsonString of(final String string) { return new ImmutableJsonString(requireNonNull(string, "The string value must not be null!")); } private  ImmutableJsonString(final String jsonString); static ImmutableJsonString of(final String string); @Override boolean isString(); @Override String asString(); @Override boolean equals(final Object o); @Override int hashCode(); @Override String toString(); @Override void writeValue(final SerializationContext serializationContext); @Override long getUpperBoundForStringSize();  }
@Test public void tryToCreateInstanceFromNullValue() { assertThatNullPointerException() .isThrownBy(() -> ImmutableJsonString.of(null)) .withMessage("The string value must not be null!") .withNoCause(); }