Adding normal metadata/object data to PDF instead of XMP metadata from InDesign CEP extension

Is there any method available which helps in inserting normal metadata/object data to the PDF document instead of XMP metadata using CEP extensions?

Because we are trying to read the metadata value with help of key using PDF Box, since there is no wrapper function available to read this data.

As of now, I could only find API to add XMP metadata, is there any API available for adding normal metadata as well?