Restore implements ContainerRenderer<C, T> on AbstractJsonViewContainerRenderer<C,T>

[jamesfredley]

The interface XXX cannot be implemented more than once with different arguments.

implements ContainerRenderer<C, T> was causing Render to be implement more than once. It is currently removed from class AbstractJsonViewContainerRenderer<C,T>

https://github.com/grails/grails-views/pull/581/files#diff-b2646b6110b34798952582e9a501678112c0ed5d810ac556902857099652a31e

[jamesfredley]

This would require changes to ContainerRenderer in grails-core.

A start: grails/grails-core@7.0.x...convert-ContainerRender-to-trait

which resulted in a deeper rabbit hole with Groovy Traits called from Java:

                Caused by:
                java.lang.NoClassDefFoundError: grails/web/mime/MimeTypeProvider$Trait$Helper
                    at org.grails.plugins.databinding.DataBindingConfiguration.xmlDataBindingSourceCreator(DataBindingConfiguration.java:68)
                    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.lambda$instantiate$0(SimpleInstantiationStrategy.java:171)
                    ... 45 more
                    Caused by:
                    java.lang.ClassNotFoundException: grails.web.mime.MimeTypeProvider$Trait$Helper
                        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
                        at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
                        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:525)
                        ... 47 more (edited) 

[jdaugherty]

I looked into this one. It's tough. It's Java code DataBindingUtils.java calling the groovy code that's failing.

Here's the grails-views code before 7.0 code:

abstract class AbstractJsonViewContainerRenderer<C,T> extends DefaultJsonRenderer<T> implements ContainerRenderer<C, T>

By specifying both interfaces, it means there are 2 identical methods returning different values. This isn't supported by Groovy 4. It's only supported by traits and loading the Groovy Object from Java code is failling. In groovy 3, it would have picked just the last interface when a method conflicts.

Maybe we shouldn't use generics, that's how others like this are working:

    class AtomCollectionRenderer extends AtomRenderer implements ContainerRenderer