code: private static Filter createFilter(final BundleContext bundleContext, final Class<?> trackedClass) {
  		final String filter = "(" + Constants.OBJECTCLASS + "=" + trackedClass.getName() + ")";
  		try {
  			return bundleContext.createFilter(filter);
  		} catch (InvalidSyntaxException e) {
  			throw new IllegalArgumentException("Unexpected InvalidSyntaxException: " + e.getMessage());
  		}
  	}
docs: Creates an OSGi filter for the classes.
  
  @param bundleContext
  a bundle context
  @param trackedClass
  the class being tracked
  @return osgi filter