If a file, for which JBoss Tools provide content extension to Project explorer, contains an error, all node icons under file node are decorated by the error icon.

The cause of that is adapting of XModelObject to IResource by implementing getAdapter(Class). It was done to fix JBIDE-7555 - since Eclipse services that init actions/wizards/etc by resources need selected object to be adaptable to IResource. But Project Explorer in decorating nodes, also adapts each node to IResource, and if the resource has error markers on it, marks each node as error node.

The solution is to adapt model object to resource not by implementing getAdapter() but by registering an adapter factory in 'org.eclipse.core.runtime.adapters'. Project Explorer does not look into factories, while other services do that.