Update Unsafe value type comments and Java methods

[theresa-m]

• update comments using primitive language
• remove stale methods getReferenceVolatile and getReference
• add methods hasNullMarker and nullMarkerOffset to match RI

Related: #19677

[hangshao0]

Jenkins compile alinuxval jdknext

[hangshao0]

Jenkins compile amac jdknext

[hangshao0]

The error in the jdkNext build (not valhalla build) is:

share/classes/java/lang/Access.java:70: error: Access is not abstract and does not override abstract method stringConcatHelperPrepend(long,byte[],String) in JavaLangAccess

Looks like jdknext is 24 and this is causing the error:

openj9/jcl/src/java.base/share/classes/java/lang/Access.java

Lines 554 to 559 in 157a0ef

	/*[IF JAVA_SPEC_VERSION < 24]*/
	@Override
	public long stringConcatHelperPrepend(long indexCoder, byte[] buf, String value) {
	return StringConcatHelper.prepend(indexCoder, buf, value);
	}
	/*[ENDIF] JAVA_SPEC_VERSION < 24 */

@JasonFengJ9

[JasonFengJ9]

The openjdk change in question is ibmruntimes/openj9-openjdk-jdk@758ebfe

It hasn't been promoted into openj9 branch yet due to abuild failure https://openj9-jenkins.osuosl.org/job/Build_JDKnext_x86-64_linux_OpenJDK/708/consoleFull

Just restarted failed JDKnext_x86-64_linux build, if it passes, the change can be pulled in manually.

[JasonFengJ9]

@hangshao0 can you retry the amac jdknext build?

[hangshao0]

Jenkins compile amac jdknext