Initialize cause of some InterruptedExceptions

Pack an OperationCanceledException inside the InterruptedException when
this is thrown due to the user canceling an operation. This makes it
easier to determine the cause of the InterruptedException from outside
the methods (i.e. in the catch-clauses). Adapt the method
ModalContext::checkCanceled accordingly. Change
WorkspaceModifyOperation::run so it preserves the original
exceptions if possible.

Same idea as
#1259

bundles/org.eclipse.ui.ide/extensions/org/eclipse/ui/actions/WorkspaceModifyOperation.java

@@ -14,6 +14,7 @@
 package org.eclipse.ui.actions;
 
 import java.lang.reflect.InvocationTargetException;
+import java.util.concurrent.atomic.AtomicReference;
 
 import org.eclipse.core.resources.IResource;
 import org.eclipse.core.resources.IWorkspaceRunnable;
@@ -103,20 +104,19 @@ protected abstract void execute(IProgressMonitor monitor)
 	@Override
 	public synchronized final void run(IProgressMonitor monitor)
 			throws InvocationTargetException, InterruptedException {
-		final InvocationTargetException[] iteHolder = new InvocationTargetException[1];
+		AtomicReference<InvocationTargetException> rethrownInvocationTargetException = new AtomicReference<>();
+		AtomicReference<InterruptedException> rethrownInterruptedException = new AtomicReference<>();
 		try {
 			IWorkspaceRunnable workspaceRunnable = pm -> {
 				try {
 					execute(pm);
 				} catch (InvocationTargetException e1) {
-					// Pass it outside the workspace runnable
-					iteHolder[0] = e1;
+					rethrownInvocationTargetException.set(e1);
 				} catch (InterruptedException e2) {
-					// Re-throw as OperationCanceledException, which will be
-					// caught and re-thrown as InterruptedException below.
-					throw new OperationCanceledException(e2.getMessage());
+					rethrownInterruptedException.set(e2);
 				}
-				// CoreException and OperationCanceledException are propagated
+				// CoreException and unchecked exceptions (e.g. OperationCanceledException) are
+				// propagated to the outer catch
 			};
 			// if we are in the UI thread, make sure we use progress monitor
 			// that spins event loop to allow processing of pending asyncExecs
@@ -137,9 +137,13 @@ public synchronized final void run(IProgressMonitor monitor)
 			interruptedException.initCause(e);
 			throw interruptedException;
 		}
-		// Re-throw the InvocationTargetException, if any occurred
-		if (iteHolder[0] != null) {
-			throw iteHolder[0];
+
+		// Re-throw any exceptions caught while running the IWorkspaceRunnable
+		if (rethrownInvocationTargetException.get() != null) {
+			throw rethrownInvocationTargetException.get();
+		}
+		if (rethrownInterruptedException.get() != null) {
+			throw rethrownInterruptedException.get();
 		}
 	}
 	@Override