Highlight or Strikeout Text, add Line or Circle Annotations in PDF using Java REST API
The content inside a PDF page is difficult to edit, but the PDF specification defines a complete set of objects that can be added to PDF pages without changing the page content. These objects are called annotations, and their purpose ranges from marking up page content to implementing interactive features such as forms.
Most PDF viewers allow the creation and editing of various annotation types, e.g. text highlights, notes, lines, or shapes, and regardless of the annotation types that are created, PDF viewers conforming to the PDF specification should also support rendering for all annotation types.