[TESTBUG]: gc/arguments/TestG1HeapRegionSize.java fails at nightly

java.lang.RuntimeException: Wrong value for G1HeapRegionSize. Expected 1048576 but got 0
at TestG1HeapRegionSize.main(TestG1HeapRegionSize.java:48)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.sun.javatest.regtest.MainWrapper$MainThread.run(MainWrapper.java:94)
at java.lang.Thread.run(Thread.java:745)


This start happening after fix of JDK-8062537. Before the fix test checked that G1 is set, and skipped if not. After update test relies on @requries and doesn't check for GC.

The test comprises 4 runs:
 * @run main/othervm -Xmx64m TestG1HeapRegionSize 1048576
 * @run main/othervm -XX:G1HeapRegionSize=2m -Xmx64m -XX:+UseG1GC TestG1HeapRegionSize 2097152
 * @run main/othervm -XX:G1HeapRegionSize=3m -Xmx64m -XX:+UseG1GC TestG1HeapRegionSize 2097152
 * @run main/othervm -XX:G1HeapRegionSize=64m -Xmx256m -XX:+UseG1GC TestG1HeapRegionSize 33554432


The first runs doesn't specify GC and fails.

Suggested fix:
 * @run main/othervm -Xmx64m TestG1HeapRegionSize 1048576
-->
 * @run main/othervm -Xmx64m -XX:+UseG1GC TestG1HeapRegionSize 1048576