Simplify conversion of ByteArrayOutputStream to String

[stsypanov]

Currently we often convert BAOS to String as

String contents = new String(baos.toByteArray(), StandardCharsets.ISO_8859_1);

which can be made more simple and effective as

String contents = baos.toString(StandardCharsets.ISO_8859_1.name());

BAOS.toByteArray() creates a copy of underlying array which is later decoded inside of String constructor, while BAOS.toString() doesn't create intermediate copy making convertion more memory-effective.

For JDK 8 I've got following results:

Benchmark                                                        (length)  Mode     Score     Error   Units
ByteArrayOutputStreamBenchmark.newString                               10  avgt    97.420 ±   7.340   ns/op
ByteArrayOutputStreamBenchmark.newString                              100  avgt   480.689 ±  20.615   ns/op
ByteArrayOutputStreamBenchmark.newString                             1000  avgt  4717.681 ± 175.550   ns/op

ByteArrayOutputStreamBenchmark.toString                                10  avgt    85.578 ±   5.233   ns/op
ByteArrayOutputStreamBenchmark.toString                               100  avgt   533.850 ±  23.902   ns/op
ByteArrayOutputStreamBenchmark.toString                              1000  avgt  4703.280 ± 113.713   ns/op

ByteArrayOutputStreamBenchmark.newString:·gc.alloc.rate.norm           10  avgt   134.400 ±  15.271    B/op
ByteArrayOutputStreamBenchmark.newString:·gc.alloc.rate.norm          100  avgt   722.401 ±  10.494    B/op
ByteArrayOutputStreamBenchmark.newString:·gc.alloc.rate.norm         1000  avgt  6380.016 ±  46.441    B/op

ByteArrayOutputStreamBenchmark.toString:·gc.alloc.rate.norm            10  avgt   109.600 ±  14.586    B/op
ByteArrayOutputStreamBenchmark.toString:·gc.alloc.rate.norm           100  avgt   664.002 ±  16.986    B/op
ByteArrayOutputStreamBenchmark.toString:·gc.alloc.rate.norm          1000  avgt  5433.618 ±  39.002    B/op

[sbrannen]

This has been merged into master in 65aa2d0 and revised in 6222efc.

Thanks