vertx-jdbc-client: UpdateResult.getKeys() returns a PGobject instead of a String

I found this issue while trying to upgrade from vert.x 3 to vert.x 4.3.3. After some testing, I noticed that it works correctly in 4.3.0 but starts failing in 4.3.1.

I have many tables with a text id and a jsonb data column. After running updateWithParams and getting the keys, I used to be able to get the data column with result.getKeys().getString(1) but that now throws an error, as the key is a PGobject instead of a string.

This can be easily reproduced by simply running the documentation code found here on vert.x 4.3.0 and again on 4.3.1+ with a jsonb column. result.getKeys() contains different values between the two.