I'll reproduce the entirety of the method() below for clarity:
The problem is when we have a RightTupleList in the last row of the table, and that list has more than one RightTuple. The call to next() that brings us to this list will increment this.row so that it's now equal to table.length. A subsequent next() should retrieve the next RightTuple, but because all of that code is conditioned on (table.row < length), the iteration ends prematurely. This affects one of my queries, which for an object with a particular hash code was only returning the first match instead of all of the matches.
I took a quick look at LeftTupleIndexHashTable.FullFastIterator, and since the code is identical, it's probably also broken.