How to maintain valid digital signatures on Android

When digitally signing documents with multiple signature fields, you need to make sure that the document can be saved incrementally. When incremental saving is disabled or not supported, PSPDFKit rewrites already signed document data, which could result in the invalidation of existing signatures.

Incremental saving is enabled only for documents that are not password protected with document sources that support appending. Appendable sources include local files and WritableDataProvider instances that return true inside WritableDataProvider#supportsAppending().