HPDFHeadlessObjectStreamBody
HPDFHeadlessObjectStreamBody(Members, DecodedBytes, MemberIndex, ExpectedObjectNumber) in HPDFHeadlessXRef returns the exact byte slice of a validated compressed object
MemberIndex is zero-based; the expected authoritative xref object number must match the indexed header number, and the slice must fit the decoded byte buffer
Failures raise EHPDFHeadlessXRefError; the document loader parses the returned body with the shared parser