Support packaging the project in JDK21 (#11528)

.github/workflows/skywalking.yaml

@@ -239,6 +239,8 @@ jobs:
         include:
           - os: ubuntu
             java-version: 17
+          - os: ubuntu
+            java-version: 21
     steps:
       - uses: actions/checkout@v3
         with:

docs/en/changes/changes.md

@@ -5,6 +5,7 @@
 * Bump Java agent to 9.1-dev in the e2e tests.
 * Bump up netty to 4.1.100.
 * Update Groovy 3 to 4.0.15.
+* Support packaging the project in JDK21. Compiler source and target remain in JDK11.
 
 #### OAP Server
 

docs/en/guides/How-to-build.md

@@ -16,7 +16,7 @@ If you need to execute build behind the proxy, edit the *.mvn/jvm.config* and se
 ```
 
 ### Building from GitHub
-1. Prepare git, JDK11+, and Maven 3.6+.
+1. Prepare git, JDK 11 or 17 (LTS versions), and Maven 3.6+.
 1. Clone the project.
 
     If you want to build a release from source codes, set a `tag name` by using `git clone -b [tag_name] ...` while cloning.

docs/en/setup/backend/backend-setup.md

@@ -14,7 +14,7 @@ SkyWalking's backend distribution package consists of the following parts:
 
 ## Requirements and default settings
 
-Requirement: **JDK11 to JDK17 are tested**. Other versions are not tested and may or may not work.
+Requirement: **JDK11 or JDK17**. 
 
 Before you begin, you should understand that the main purpose of the following quickstart is to help you obtain a basic configuration for previews/demos. Performance and long-term running are **NOT** among the purposes of the quickstart.
 

pom.xml

@@ -153,11 +153,14 @@
         <!-- `project.build.outputTimestamp` is required for reproducible builds: https://maven.apache.org/guides/mini/guide-reproducible-builds.html -->
         <project.build.outputTimestamp>1693572743</project.build.outputTimestamp>
 
+        <!-- Compiling and test stages tools. -->
         <powermock.version>2.0.9</powermock.version>
         <checkstyle.version>6.18</checkstyle.version>
         <junit.version>5.9.2</junit.version>
         <mockito-core.version>4.11.0</mockito-core.version>
-        <lombok.version>1.18.22</lombok.version>
+        <system-stubs.version>2.1.4</system-stubs.version>
+        <lombok.version>1.18.30</lombok.version>
+        <byte-buddy.version>1.14.9</byte-buddy.version>
 
         <!-- core lib dependency -->
         <grpc.version>1.53.0</grpc.version>
@@ -194,8 +197,6 @@
         <skipUTs>false</skipUTs>
         <argLine>--add-opens java.base/java.lang=ALL-UNNAMED</argLine>
 
-        <system-stubs.version>2.0.2</system-stubs.version>
-
         <delombok.output.dir>${project.build.directory}/delombok</delombok.output.dir>
     </properties>
 
@@ -284,6 +285,28 @@
                 <artifactId>mockito-junit-jupiter</artifactId>
                 <version>${mockito-core.version}</version>
                 <scope>test</scope>
+                <exclusions>
+                    <exclusion>
+                        <groupId>net.bytebuddy</groupId>
+                        <artifactId>byte-buddy</artifactId>
+                    </exclusion>
+                    <exclusion>
+                        <groupId>net.bytebuddy</groupId>
+                        <artifactId>byte-buddy-agent</artifactId>
+                    </exclusion>
+                </exclusions>
+            </dependency>
+            <dependency>
+                <groupId>net.bytebuddy</groupId>
+                <artifactId>byte-buddy</artifactId>
+                <version>${byte-buddy.version}</version>
+                <scope>test</scope>
+            </dependency>
+            <dependency>
+                <groupId>net.bytebuddy</groupId>
+                <artifactId>byte-buddy-agent</artifactId>
+                <version>${byte-buddy.version}</version>
+                <scope>test</scope>
             </dependency>
 
             <dependency>
@@ -303,6 +326,16 @@
                 <artifactId>system-stubs-jupiter</artifactId>
                 <version>${system-stubs.version}</version>
                 <scope>test</scope>
+                <exclusions>
+                    <exclusion>
+                        <groupId>net.bytebuddy</groupId>
+                        <artifactId>byte-buddy</artifactId>
+                    </exclusion>
+                    <exclusion>
+                        <groupId>net.bytebuddy</groupId>
+                        <artifactId>byte-buddy-agent</artifactId>
+                    </exclusion>
+                </exclusions>
             </dependency>
 
             <dependency>