Revisit Java invocation build sequence logic in STF

[Mesbah-Alam]

STF enforces a particular order in which we can define a LoadTestProcessDefinition instance. This enforcement can cause STF test plugins to become complicated (or less simple than what is desirable). For example:

LoadTestProcessDefinition loadTestInvocation = test.createLoadTestSpecification()
				.addJvmOption("-Djava.classloading.dir=" + notonclasspathDirRoot)  // Expose the bin_notonclasspath root directory to the deadlock test
				.addJvmOption("-Djava.version.number=" + javaVersion)
				.addModules(modulesAdd)
				.addPrereqJarToClasspath(JavaProcessDefinition.JarId.JUNIT)
				.addPrereqJarToClasspath(JavaProcessDefinition.JarId.HAMCREST)
				.addProjectToClasspath("openjdk.test.classloading"); 
		
		if (isTimeBasedLoadTest) { 
			loadTestInvocation = loadTestInvocation.setTimeLimit(timeLimit); // If it's a time based test, stop execution after given time duration
		}
		
		loadTestInvocation = loadTestInvocation.setAbortIfOutOfMemory(false)
				.addSuite("classloading")
				.setSuiteThreadCount(cpuCount - 1, 10)
				.setSuiteInventory(inventoryFile);
		
		if (!isTimeBasedLoadTest) { 
			loadTestInvocation = loadTestInvocation.setSuiteNumTests(totalTests * testCountMultiplier);
		}
			
		loadTestInvocation = loadTestInvocation.setSuiteRandomSelection();

The above definition could be simpler, if STF allowed the following:

LoadTestProcessDefinition loadTestInvocation = test.createLoadTestSpecification()
				.addJvmOption("-Djava.classloading.dir=" + notonclasspathDirRoot)  // Expose the bin_notonclasspath root directory to the deadlock test
				.addJvmOption("-Djava.version.number=" + javaVersion)
				.addModules(modulesAdd)
				.addPrereqJarToClasspath(JavaProcessDefinition.JarId.JUNIT)
				.addPrereqJarToClasspath(JavaProcessDefinition.JarId.HAMCREST)
				.addProjectToClasspath("openjdk.test.classloading")	
				.setAbortIfOutOfMemory(false)
				.addSuite("classloading");
		
		if (isTimeBasedLoadTest) { 
			loadTestInvocation = loadTestInvocation.setTimeLimit(timeLimit); // If it's a time based test, stop execution after given time duration
		} else { 
			loadTestInvocation = loadTestInvocation.setSuiteNumTests(totalTests * testCountMultiplier);
		}
		
		loadTestInvocation = loadTestInvocation.setSuiteThreadCount(cpuCount - 1, 10)
				.setSuiteInventory(inventoryFile)
				.setSuiteRandomSelection();

This issue is opened to revisit the design principles of these order enforcements and update the logic therein if possible.

FYI @llxia