treating not null and null with new resources of Java 8

Treating null and not null using java.util.Objects will faster than using operator, because the JIT action.
Running the bench with JMH[1] the result was:

Benchmark                         (size)   Mode   Samples         Mean   Mean error    Units
m.NullBenchmark.isNotNull        1000000  thrpt        20      251.020       36.826    ops/s
m.NullBenchmark.isNotNullUtils   1000000  thrpt        20      286.275        2.388    ops/s
m.NullBenchmark.isNull           1000000  thrpt        20      289.536        2.463    ops/s
m.NullBenchmark.isNullUtils      1000000  thrpt        20      290.583        2.101    ops/s

Another points of null can replace with Optional or using new methods on map.

[1] http://openjdk.java.net/projects/code-tools/jmh/