code: public static ClassLoader overrideThreadContextClassLoader(ClassLoader classLoaderToUse) {
  		Thread currentThread = Thread.currentThread();
  		ClassLoader threadContextClassLoader = currentThread.getContextClassLoader();
  		if (classLoaderToUse != null && !classLoaderToUse.equals(threadContextClassLoader)) {
  			currentThread.setContextClassLoader(classLoaderToUse);
  			return threadContextClassLoader;
  		}
  		else {
  			return null;
  		}
  	}
docs: Override the thread context ClassLoader with the environment's bean ClassLoader
  if necessary, i.e. if the bean ClassLoader is not equivalent to the thread
  context ClassLoader already.
  @param classLoaderToUse the actual ClassLoader to use for the thread context
  @return the original thread context ClassLoader, or {@code null} if not overridden