`xpp3-extended-writer` produces erroneous class name (`null` rather than `Ex`)

[mykelalvis]

When location tracking is active, Xpp3WriterGenerator#initialize forces the variable extendedClassnameSuffix to be set to the ModelloParameterConstants.EXTENDED_CLASSNAME_SUFFIX property that was passed into the #initialize call higher in the call hierarchy.

EXTENDED_CLASSNAME_SUFFIX apparently does get set in the ModelloXpp3ExtendedWriterMojo#customizeParameters but apparently does not get set at any point in the generate MOJO's call. This causes generate executions using xpp3-extended-writer to use the value null for extendedClassnameSuffix resulting in a generated marshallerName of XXXXXXpp3Writernull rather than XXXXXXXpp3WriterEx.

The xpp3-extended-reader uses a different method to calculate the extension value, and thus does not suffer from this bug.

[kwin]

@mykelalvis Thanks for the report, can you come up with a test case for this and in the best case also a fix as PR?

[mykelalvis]

Due to a version override, I was probably using a much older version of modello within the codebase that used this.

This has been reworked in 2.x+, so I'm closing this.