Get the number of changes that have been made after this signature. For PDF documents, you can find out what changes have been made to the document between this signature and the next one (or after the last signature if this is the last signature). Computing the changes can be expensive. Changes are not reported in any particular order; before presenting them to a user, you should group them. Detecting and categorizing changes is work in progress. Moreover, it will never be bug-compatible with Adobe products.

public int getChangeCount()