Remove jdk9-compile profile from pom.xml

[zrlw]

What's Changed

1. Remove jdk9-compile profile configuration from pom.xml. For now, Unsafe will be considered as nonexistent package if set maven.compiler.release, no matter the release is set to 8 or not. see details at There are difference between maven.compiler.release and maven.compiler.target during compiling projects which use sun.misc.Unsafe with JDK17+ maven-compiler-plugin#990
2. Call position method of java.nio.Buffer instead of java.nio.ByteBuffer for the sake of jdk8 compatibility since position method had been moved from java.nio.Buffer to its subclass java.nio.ByteBuffer since jdk9+.

What is the purpose of the change?

The release configuration of jdk9-compile profile will cause trouble if we compile dubbo with jdk17+ and use sun.misc.Unsafe like this,

import sun.misc.Unsafe;

import static org.apache.dubbo.common.constants.CommonConstants.ThirdPartyProperty.GRAALVM_NATIVEIMAGE_IMAGECODE;

public abstract class NativeDetector {
    private Unsafe UNSAFE;
    ...

Cause

sun.misc.Unsafe had been moved to jdk.unsupported module since jdk9+, it could not be added if set maven.compiler.release

When using --release to specify a release that supports the Java Platform Module System, the --add-exports option cannot be used to enlarge the set of packages exported by the Java SE, JDK, and standard modules in the specified release.

see details at https://docs.oracle.com/en/java/javase/25/docs/specs/man/javac.html#option-release

Checklist

• Make sure there is a GitHub_issue field for the change.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Write necessary unit-test to verify your logic correction. If the new feature or significant change is committed, please remember to add sample in dubbo samples project.
• Make sure gitHub actions can pass. Why the workflow is failing and how to fix it?

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.72%. Comparing base (84c4802) to head (445c86c).

Additional details and impacted files

@@            Coverage Diff            @@
##                3.3   #15755   +/-   ##
=========================================
  Coverage     60.72%   60.72%           
- Complexity    11695    11708   +13     
=========================================
  Files          1938     1938           
  Lines         88637    88637           
  Branches      13380    13380           
=========================================
+ Hits          53825    53828    +3     
+ Misses        29288    29285    -3     
  Partials       5524     5524           

Flag	Coverage Δ
integration-tests-java21	32.40% <100.00%> (+0.01%)	⬆️
integration-tests-java8	32.52% <100.00%> (+0.06%)	⬆️
samples-tests-java21	32.03% <100.00%> (+0.03%)	⬆️
samples-tests-java8	29.61% <100.00%> (-0.04%)	⬇️
unit-tests-java11	59.02% <100.00%> (-0.01%)	⬇️
unit-tests-java17	58.53% <100.00%> (+0.02%)	⬆️
unit-tests-java21	58.50% <100.00%> (-0.02%)	⬇️
unit-tests-java25	58.47% <100.00%> (-0.03%)	⬇️
unit-tests-java8	58.99% <100.00%> (-0.01%)	⬇️

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