private void installPlaceholder(ComponentPlaceholder placeholder) {

		Set<ComponentPlaceholder> activePlaceholders =
			getActivePlaceholdersByOwner(placeholder.getOwner());
		registerPlaceholder(placeholder);
		positionNewPlaceholder(activePlaceholders, placeholder);
	}
Finds or creates a component placeholder object for the given provider.
@param provider the provider for which to get an placeholder object.
@param defaultPlaceholder the placeholder to use if an existing one cannot be found
@return a component placeholder object that will be used to manager the providers component.
Ghidra/Framework/Docking/src/main/java/docking/PlaceholderManager.java