Only attempt to load from persistent cache if the model has not yet been loaded.
JavaExtensionNodes now notifies the project of the changes in the nodes.
JavaDependenciesNode is now refreshed when needed (lazy).
Fixed a node refresh condition in JavaExtensionNodes.
Removed out-of-date comment from JavaDependenciesNode.
Project nodes are no longer refreshed for each model (re)load.
Fixed an issue where the project nodes were not refreshed when a new source set was added.
The subproject node is now refreshed when a subproject is added or removed.
Project node is now refreshed after subprojects are added and there was none yet.
Fixed an issue where the project node was needlessly refreshed on the first project reload due to the subprojects and dependencies node.