LedgerEntry#getLength does not do what the documentation says

You would expect getLength on a LedgerEntry to return the length of the data in the entry. The documentation says it does this, and the Mock implementation do so too. But this is not what it does. It in fact returns the length of the ledger up to and including this entry.

At the very least this is a documentation bug, but this name is super confusing even if the documentation is updated.