Changed to field updater
Performance Tests and Subscription Wrapper Removal

- increase from 7.7m ops/second to 8.8m by eliminating Subscription wrapper

../gradlew benchmarks '-Pjmh=-f 1 -tu s -bm thrpt -wi 5 -i 5 -r 5 -prof GC .*PerfTransforms.mapTransformation*'

Before changes

Benchmark                              (size)   Mode   Samples         Mean   Mean error    Units
r.u.PerfTransforms.mapTransformation        1  thrpt         5  7714453.187   362218.633    ops/s
r.u.PerfTransforms.mapTransformation        1  thrpt         5  7527144.767   497816.471    ops/s

After remove wrapper subscription:

Benchmark                              (size)   Mode   Samples         Mean   Mean error    Units
r.u.PerfTransforms.mapTransformation        1  thrpt         5  8853534.333   183494.242    ops/s
r.u.PerfTransforms.mapTransformation        1  thrpt         5  8806958.403   452595.219    ops/s