Enum valueForString methods are not consistent

[mikeburke106]

See PR #82 for more details.

Most enum classes simply use the name() method to define the value of the JSON value for each particular enum value. Therefore, the valueForString method typically calls and returns the result of the valueOf() method.

If valueForString is called with a JSON value that is not contained in the enum, the valueOf method will cause an IllegalArgumentException.

However, in enum classes that define their own internal name to represent the JSON value, the valueForString method loops through all enum values and returns the value if it's found. If it's not found, it will return null.

All enums should behave identically in this case, so we need to determine if the correct course of action is to throw a RuntimeException (causing a crash) or to return null.

[mikeburke106]

Ok, so let me put this in a form of a question. When we get an invalid JSON enum value as part of a message from SDL core and call valueForString() on the enum class in question, do we expect:

1. Return null - it will be as if the value was omitted from the JSON string, but app runs as normal
2. Throw IllegalArgumentException - app will crash with Runtime exception

Similarly, what should happen if we pass in null to valueForString()?

1. Return null - it will be as if the value was omitted from the JSON string, but app runs as normal
2. Throw NullPointerException - app will crash with Runtime exception

This case "should never happen", but in case it does, I'm of the opinion that we should return null instead of crashing the application. Does anyone else have an opinion?

This would involve re-writing the valueForString() methods to look something like this:

public static AppInterfaceUnregisteredReason valueForString(String value) {
    try{
        return valueOf(value);
    }
    catch(Exception e){ //IllegalArgumentException or NullPointerException
        return null;
    }
}