Flatten all annotations of the document or of a range of pages. Flattening an annotation of a PDF document makes its appearance part of the page and removes the selected annotation or all annotations. This function selects all non-widget annotations on the specified pages, ie, it does not flatten fields. Flattening annotations breaks existing signatures. If you are flattening annotations only for printing with PDF components that don't support annotations, make a copy of the document, pass

public void flattenAnnotations(
	int firstPage,
	int lastPage,
	FlattenAnnotationsFlags flags
)