What is the purpose of this PR

• The purpose of this PR is to resolve the unpredictability caused by the flaky test: org.apache.dubbo.common.bytecode.WrapperTest.est_getMethodNames_ContainExtendsParentMethods.
• The test passes/fails based on the ordering of the names of methods returned bygetMethodNames methods from Wrapper and ClassUtils classes.

Why the test fail

• The test asserts whether a certain array containing the names of the methods is available in the aforementioned classes.
• The problem, however, arises because the order in which the names would be returned is not guaranteed by the method used to retrieve the names.
• But assertArrayEquals expects even the order of the array elements to match - hence sometimes causing the failure.

How to reproduce the test failure

• The scenario may be reproduced by running the tests with Nondex tool:

• `mvn -pl dubbo-common edu.illinois:nondex-maven-plugin:2.1.7:nondex -Dtest=org.apache.dubbo.common.bytecode.WrapperTest#test_getMethodNames_ContainExtendsParentMethods`
  

• Instructions on Nondex installation may be found here.

Expected results

The test should run successfully with Nondex instrumentation.

Actual Results

• Following error result is obtained upon running the original code with Nondex:
• [ERROR] Failed to execute goal edu.illinois:nondex-maven-plugin:2.1.7:nondex (default-cli) on project dubbo-common: Unable to execute mojo: There are test failures.
• Evidence that the test is indeed failing due to the difference in ordering can be observed in the following line:
• [ERROR] WrapperTest.test_getMethodNames_ContainExtendsParentMethods:184 array contents differ at index [0], expected: <hello> but was: <world>

Description of fix

• The idea is to sort the array containing the names of methods before asserting.
• This can be performed using the sort method of java.util as in Arrays.sort(methodNames).