[memory] JavaBuilder.oldState leaks into Workspace.tree

In the heapdump of https://github.com/eclipse-platform/eclipse.platform.releng.aggregator/pull/1612 most memory was hold by org.eclipse.core.internal.resources.Workspace.tree.
VisualVM:

JDKMC:

Workspace.tree is meant to store the state of the Workspace. It does so by storing the history of changes (DeltaDataTree) to the workspace. Interestingly the workspace also stores all IncrementalBuilders which again contain references to the old trees.
I.e the Workspace stores a history of things that contain their history.
That org.eclipse.core.internal.events.InternalBuilder.oldState sounds like a leak - or say - something that unintentionally stores more memory then intended.

I have however no idea how to reduce that since an IncrementalBuilders needs to know the oldState to calculate increments. Just that the old state is stored again as a history feels odd.

Usa el análisis del heap dump enlazado como punto de partida y, después, lee Workspace.tree, DeltaDataTree e InternalBuilder.oldState, incluidas las referencias a oldState de JavaBuilder. Rastrea por qué el estado del builder sigue retenido e identifica el ciclo de vida previsto; el issue estará terminado cuando un enfoque revisado reduzca la retención no intencionada e incluya pruebas de que las compilaciones incrementales siguen funcionando correctamente.

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