Bug 250133 [Contexts] ContextAction's leak when hiding actions sets
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/contexts/ContextManager.java
handleObjectsById.put(contextId, context);
			context.addContextListener(this);
		}
		return context;
	}
	/**
	 * Returns the set of identifiers for those contexts that are defined.
	 * 
	 * @return The set of defined context identifiers; this value may be empty,
	 *         but it is never <code>null</code>.
	 */
	public final Set getDefinedContextIds() {
		return getDefinedHandleObjectIds();
	}
	/**
	 * Returns the those contexts that are defined.
	 * 
	 * @return The defined contexts; this value may be empty, but it is never
	 *         <code>null</code>.
	 * @since 3.2
	 */
	public final Context[] getDefinedContexts() {
		return (Context[]) definedHandleObjects
				.toArray(new Context[definedHandleObjects.size()]);
	}
	/**
	 * Deactivates a context in this context manager.
	 * 
	 * @param contextId
	 *            The identifier of the context to deactivate; must not be