THRIFT-5521: [java gen] use jdk8 option type in java generator code
Client: Java
Patch: Jiayu Liu

This closes #2525
diff --git a/lib/java/gradle/generateTestThrift.gradle b/lib/java/gradle/generateTestThrift.gradle
index d5bc3af..c48845e 100644
--- a/lib/java/gradle/generateTestThrift.gradle
+++ b/lib/java/gradle/generateTestThrift.gradle
@@ -24,11 +24,12 @@
 ext.genBeanSrc = file("$buildDir/gen-javabean")
 ext.genReuseSrc = file("$buildDir/gen-javareuse")
 ext.genFullCamelSrc = file("$buildDir/gen-fullcamel")
+ext.genOptionTypeJdk8Src = file("$buildDir/gen-option-type-jdk8")
 ext.genUnsafeSrc = file("$buildDir/gen-unsafe")
 
 // Add the generated code directories to the test source set
 sourceSets {
-    test.java.srcDirs genSrc, genBeanSrc, genReuseSrc, genFullCamelSrc, genUnsafeSrc
+    test.java.srcDirs genSrc, genBeanSrc, genReuseSrc, genFullCamelSrc, genUnsafeSrc, genOptionTypeJdk8Src
 }
 
 // ----------------------------------------------------------------------------
@@ -37,7 +38,10 @@
 // A callable closure to make this easier
 ext.thriftCompile = { Task task, String thriftFileName, String generator = 'java', File outputDir = genSrc ->
     def thriftFile = file("$thriftRoot/test/$thriftFileName")
-    assert thriftFile.exists()
+    if (!thriftFile.exists()) {
+        thriftFile = file("$projectDir/test/resources/$thriftFileName")
+        assert thriftFile.exists(), "can't find $thriftFile"
+    }
 
     task.inputs.file thriftFile
     task.outputs.dir outputDir
@@ -85,6 +89,15 @@
     thriftCompile(it, 'partial/thrift_test_schema.thrift')
 }
 
+task generateOptionalTypeJava(group: 'Build') {
+    description = 'Generate the thrift gen-option-type-jdk8 source'
+    generate.dependsOn it
+
+    ext.outputBuffer = new ByteArrayOutputStream()
+
+    thriftCompile(it, 'JavaOptionTypeJdk8Test.thrift', 'java:option_type=jdk8', genOptionTypeJdk8Src)
+}
+
 task generateBeanJava(group: 'Build') {
     description = 'Generate the thrift gen-javabean source'
     generate.dependsOn it