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)

Same idea as
eclipse-platform/eclipse.platform.ui#1259

runtime/bundles/org.eclipse.core.tools/src/org/eclipse/core/tools/search/FindUnusedMembers.java

@@ -17,10 +17,30 @@
 import java.io.IOException;
 import java.io.Writer;
 import java.lang.reflect.InvocationTargetException;
-import org.eclipse.core.runtime.*;
-import org.eclipse.jdt.core.*;
-import org.eclipse.jdt.core.dom.*;
-import org.eclipse.jdt.core.search.*;
+import org.eclipse.core.runtime.CoreException;
+import org.eclipse.core.runtime.IProgressMonitor;
+import org.eclipse.core.runtime.OperationCanceledException;
+import org.eclipse.core.runtime.SubMonitor;
+import org.eclipse.jdt.core.ICompilationUnit;
+import org.eclipse.jdt.core.IField;
+import org.eclipse.jdt.core.IMember;
+import org.eclipse.jdt.core.IMethod;
+import org.eclipse.jdt.core.IType;
+import org.eclipse.jdt.core.JavaModelException;
+import org.eclipse.jdt.core.Signature;
+import org.eclipse.jdt.core.dom.AST;
+import org.eclipse.jdt.core.dom.ASTParser;
+import org.eclipse.jdt.core.dom.IBinding;
+import org.eclipse.jdt.core.dom.IMethodBinding;
+import org.eclipse.jdt.core.dom.ITypeBinding;
+import org.eclipse.jdt.core.dom.IVariableBinding;
+import org.eclipse.jdt.core.search.IJavaSearchConstants;
+import org.eclipse.jdt.core.search.IJavaSearchScope;
+import org.eclipse.jdt.core.search.SearchEngine;
+import org.eclipse.jdt.core.search.SearchMatch;
+import org.eclipse.jdt.core.search.SearchParticipant;
+import org.eclipse.jdt.core.search.SearchPattern;
+import org.eclipse.jdt.core.search.SearchRequestor;
 import org.eclipse.jdt.internal.corext.dom.Bindings;
 import org.eclipse.jdt.internal.corext.refactoring.RefactoringScopeFactory;
 import org.eclipse.jface.operation.IRunnableWithProgress;
@@ -202,7 +222,9 @@ public void run(IProgressMonitor monitor) throws InvocationTargetException, Inte
  try {
  process(monitor);
  } catch (OperationCanceledException e) {
- throw new InterruptedException();
+ InterruptedException interruptedException = new InterruptedException(e.getMessage());
+ interruptedException.initCause(e);
+ throw interruptedException;
  } catch (CoreException e) {
  throw new InvocationTargetException(e);
  }