code: public static boolean installed(Class<?> component) {
  		Preconditions.checkState(container != null, 
  				"Cannot indicate if the specified component has been installed " +
  				"until Jaguar starts");
  		return container.installed(component);
  	}
docs: Indicates the specified component installed or not.
  
  @param component The component class to be examined.
  @return <code>true</code> if the specified component installed.