[Java] Fix java doc building error (#10757)

java/api/src/main/java/io/ray/api/call/BaseActorCreator.java

@@ -89,7 +89,7 @@ public class BaseActorCreator<T extends BaseActorCreator> {
    * Set the max number of concurrent calls to allow for this actor.
    * <p>
    * The max concurrency defaults to 1 for threaded execution.
-   * Note that the execution order is not guaranteed when max_concurrency > 1.
+   * Note that the execution order is not guaranteed when {@code max_concurrency > 1}.
    *
    * @param maxConcurrency The max number of concurrent calls to allow for this actor.
    * @return self

java/api/src/main/java/io/ray/api/options/ActorCreationOptions.java

@@ -129,7 +129,7 @@ public class ActorCreationOptions extends BaseTaskOptions {
      * Set the max number of concurrent calls to allow for this actor.
      * <p>
      * The max concurrency defaults to 1 for threaded execution.
-     * Note that the execution order is not guaranteed when max_concurrency > 1.
+     * Note that the execution order is not guaranteed when {@code max_concurrency > 1}.
      *
      * @param maxConcurrency The max number of concurrent calls to allow for this actor.
      * @return self

java/build-jar-multiplatform.sh

@@ -17,6 +17,15 @@ cd "$WORKSPACE_DIR/java"
 version=$(python -c "import xml.etree.ElementTree as ET;  r = ET.parse('pom.xml').getroot(); print(r.find(r.tag.replace('project', 'version')).text);" | tail -n 1)
 cd -
 
+check_java_version() {
+  local VERSION
+  VERSION=$(java  -version 2>&1 | awk -F '"' '/version/ {print $2}')
+  if [[ ! $VERSION =~ 1.8 ]]; then
+    echo "Java version is $VERSION. Please install jkd8."
+    exit 1
+  fi
+}
+
 build_jars() {
   local platform="$1"
   local bazel_build="${2:-true}"
@@ -180,6 +189,8 @@ deploy_jars() {
   fi
 }
 
+check_java_version
+
 case "$1" in
 linux) # build jars that only contains Linux binaries.
   build_jars_linux

java/pom.xml

@@ -124,7 +124,7 @@
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-javadoc-plugin</artifactId>
-          <version>2.10.4</version>
+          <version>3.1.0</version>
           <executions>
             <execution>
               <id>attach-javadocs</id>

java/test.sh

@@ -6,6 +6,7 @@ set -e
 set -x
 
 ROOT_DIR=$(cd "$(dirname "${BASH_SOURCE:-$0}")"; pwd)
+java -version
 
 run_testng() {
     local exit_code