Re-add java compilation source compatibility as Java 8 for servlet jakarta.

Author: kannanjgithub

gradle/libs.versions.toml

@@ -54,7 +54,7 @@ hdrhistogram = "org.hdrhistogram:HdrHistogram:2.2.2"
 # 6.0.0+ use java.lang.Deprecated forRemoval and since from Java 9
 jakarta-servlet-api = "jakarta.servlet:jakarta.servlet-api:5.0.0"
 # Using javax.annotation is fine as it is part of the JDK, we don't want to depend on J2EE
-# where it is relocated to as org.apache.tomcat:tomcat-annotations-api. See issue #7179.
+# where it is relocated to as org.apache.tomcat:tomcat-annotations-api. See issue #9179.
 javax-annotation = "org.apache.tomcat:annotations-api:6.0.53"
 javax-servlet-api = "javax.servlet:javax.servlet-api:4.0.1"
 # 12.0.0+ require Java 17+

servlet/jakarta/build.gradle

@@ -37,6 +37,11 @@ configurations {
     undertowTestImplementation.extendsFrom(itImplementation)
 }
 
+java {
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
+}
+
 // Mechanically transform sources from grpc-servlet to use the corrected packages
 def migrate(String name, String inputDir, SourceSet sourceSet) {
     def outputDir = layout.buildDirectory.dir('generated/sources/jakarta-' + name)