[REQ] [java] [restclient] [webclient] Equals and hashcode implementation for static singleRequestParameter model

[Mattias-Sehlstedt]

Is your feature request related to a problem? Please describe.

The class that is generated when using the "useSingleRequestParameter" option with static for the Java Spring-client could preferably have an implementation for equals and hashcode so the model is easier to use.

For example in a testing context with Mockito where the service is instantiating the class with a number of parameters and the mock is then ensuring that the apiClient is invoked with the correct "EXPECTED_PARAMETER" instance.

int param1 = 1;
int param2 = 2;
SingleRequestParam EXPECTED = new SingleRequestParam().param1(param1).param2(param2);    

@Test
void test() {
    service.call(param1, param2);

    verify(apiClient, times(1)).call(EXPECTED);
}

Describe the solution you'd like

The class defines an equals and a hashcode that compares the values of the variables of the class.

Describe alternatives you've considered

Letting the openapi-generator user define it themselves (e.g., either by overriding the implementation themselves, or by using lombok or similar).

Additional context