Blocker: one does not change ANYTHING in model, just updates modello from 2.4.0 to 2.5.0 and project explodes

[cstamas]

Cause:
#493

Example project:
https://github.com/takari/takari-lifecycle

It uses modello 2.4.0 but if you up modello to 2.5.0 it explodes. Reason is the singular/plural change. Modello 2.4.0 generated code wrote XML as:

    <superclasses>
      <superclasse>io.takari.lifecycle.uts.plugindescriptor.LegacyMojo</superclasse>
      <superclasse>org.apache.maven.plugin.AbstractMojo</superclasse>
    </superclasses>

Modello 2.5.0 fixes this, inner element becomes superclass. But, generated reader loses all ability to read XML written out by writer that was generated from SAME model using Modello 2.4.0. In other words: same model generated by modello 2.4.0 and 2.5.0 are not compatible.

Typically, the Takari incremental build project https://github.com/takari/io.takari.incrementalbuild uses Takari Lifecycle as well, so it already contains metadata generated by (released) Lifecycle, and it will contain superclasse. In Lifecycle build itself, IF I up modello to 2.5.0, code suddenly loses ability to read existing descriptors, and all explodes.

[cstamas]

While this change (singular/plural) sounds okay and is okay for new projects, for projects with long model history is totally breaking (same stands for maven!). Suddenly all the existing written out XML even with same model is not readable anymore.

I see as solution:

• either a config switch to enable/disable this behaviour and fallback to "old" (bad) singular/plural code
• lax readers and allow "broken" singlar tags to be readed as well, but this would violate generated XSD as well

The construct is question is:

        <field>
          <name>superclasses</name>
          <association>
            <type>String</type>
            <multiplicity>*</multiplicity>
          </association>
        </field>

And the new code does suplerclasses -> superclass but rejects old tags superclasse.

In fact, on projects where a long history of releases exists, this change should have not even applied IMO for the reason explained above (no change in model, but it renders all existing written out XMLs invalid).

[slawekjaranowski]

There is a new parameter: pluralExceptions https://codehaus-plexus.github.io/modello/modello-maven-plugin/java-mojo.html#pluralExceptions

so you can add to project:

<pluralExceptions>
  <superclasses>superclasse</superclasses>
</pluralExceptions>

[cstamas]

Good, but my problem is following: I don't know which other field may be affected as well.

[slawekjaranowski]

Good, but my problem is following: I don't know which other field may be affected as well.

Right .... if your text doesn't cover it can be difficult to guess

So what is proposition to resolve it ...?

[slawekjaranowski]

I see:

config switch to enable/disable this behaviour and fallback to "old" (bad) singular/plural code

[slawekjaranowski]

We can also return to old implementation with empty exceptions .. and project which need something else will add what needs