class file format issue

I appears to me that the latest jdbc4 driver is compiled with a wrong
class file format.

unzip -q -c postgresql-9.4-1201.jdbc41.jar org/postgresql/PGStatement.class | od -t x1u1 -N 10
0000000  ca  fe  ba  be  00  00  00  33  00  23
        202 254 186 190   0   0   0  51   0  35

The above is OK.

unzip -q -c postgresql-9.4-1201.jdbc4.jar org/postgresql/PGStatement.class | od -t x1u1 -N 10
0000000  ca  fe  ba  be  00  00  00  33  00  23
        202 254 186 190   0   0   0  51   0  35

That should be "50" instead of "51".

As a result, loading this driver with Java 1.6.0 results in

java.lang.UnsupportedClassVersionError: org/postgresql/Driver : Unsupported major.minor version 51.0