RFR: 8293432: Use diamond operator in java.management

[Andrey Turbanov]

The diamond operator was introduced in Java 7. We can take advantage of this language feature to make code easier to read.
Tested on Linux release x64. `make test TEST="jdk/java/lang/management jdk/javax/management jdk/com/sun/jmx jdk/sun/management"`

Test summary
==============================
   TEST                                              TOTAL  PASS  FAIL ERROR   
   jtreg:test/jdk/java/lang/management                  69    69     0     0   
   jtreg:test/jdk/javax/management                     246   246     0     0   
   jtreg:test/jdk/com/sun/jmx                            3     3     0     0   
>> jtreg:test/jdk/sun/management                        33    32     0     1 <<

Single failure - is a test `RmiBootstrapTest.java#id1`. It's known issue - [JDK-8293335](https://bugs.openjdk.org/browse/JDK-8293335).

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Commit messages:
 - [PATCH] Use diamond operator in java.management

Changes: https://git.openjdk.org/jdk/pull/10173/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10173&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8293432
  Stats: 363 lines in 61 files changed: 2 ins; 72 del; 289 mod
  Patch: https://git.openjdk.org/jdk/pull/10173.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10173/head:pull/10173

PR: https://git.openjdk.org/jdk/pull/10173