kerberos pg_ident different behavior in psql vs. jdbc

I have installed PostgreSQL 9.4 and MIT Kerberos 5 on an Ubuntu 15.10
system.

I have added the following entries:

pg_hba.conf:

1. # TYPE DATABASE USER ADDRESS
METHOD OPTIONS
2. host all all 52.34.69.195/32 gss
include_realm=1 map=gss krb_realm=INVARIANTPROPERTIES.COM

pg_ident.conf:

1. # MAPNAME SYSTEM-USERNAME
PG-USERNAME
2. gss /^([^/]+)\/postgres(at)INVARIANTPROPERTIES\(dot)COM$ \1

If I kinit the principal 'bgiles/postgres(at)INVARIANTPROPERTIES(dot)COM' I can
successfully connect to the database as the 'bgiles' user. I have
confidence is the PostgreSQL configuration.

I can take the keytab file containing the key, add a JAAS configuration
file, and successfully authenticate to the KDC. I have confidence that
that's correct although there might be small tweaks possible. (E.g., should
the JAAS principal field include @REALM?)

However when I try to connect via JDBC (using JAAS and a keytab file) I
seem to fail at the pg_ident.conf step.

2016-04-21 19:36:22 UTC [10992-2] bgiles/postgres(at)SNAPLOGIC(dot)COM@bgiles LOG:
no match in usermap "gss" for user "bgiles/postgres" authenticated as
"bgiles/postgres(at)SNAPLOGIC(dot)COM"
2016-04-21 19:36:22 UTC [10992-3] bgiles/postgres(at)SNAPLOGIC(dot)COM@bgiles
FATAL: GSSAPI authentication failed for user "bgiles/postgres(at)SNAPLOGIC(dot)COM
"
2016-04-21 19:36:22 UTC [10992-4] bgiles/postgres(at)SNAPLOGIC(dot)COM@bgiles
DETAIL: Connection matched pg_hba.conf line 100: "host all all
75.144.16.201/32 gss include_realm=1 map=gss krb_realm=SNAPLOGIC.COM"

​That happens with a jdbc username of 'bgiles', 'bgiles/postgres', or
'bgiles/postgres(at)SNAPLOGIC(dot)COM'.

Have other people looked at Kerberos + JDBC? I'm also looking at the JDBC
driver code and I might have noticed something that would cause problems
but I wanted to check with others before I tried hacking on it.

Thanks,

Bear