Expressiveness of SQLException

Hello dear developers,

I wrote a function for the server, that rises this error when called
(called and displayed in PGAdmin III):

    ERROR: value too long for type character varying(255)
    SQL Status:22001
    Kontext:PL/pgSQL function "fkt_calculateshoppinglistitems" line 26
at assignment
    PL/pgSQL function "fkt_calculateallshoppinglistitems" line 16 at FOR
over SELECT rows

When this function is called by JDBC, the only information stored in the
exception is:

     ERROR: value too long for type character varying(255)

Which makes debugging from server logfiles much harder. I expected to
have some more exceptions encapsulated (retrievable with
getNextException on PSQLException), but found nothing.

Where do I have to look for the missing information?

With best regards,
Daniel Migowski