Support Gradle annotation processing (#2793)

Signed-off-by: Sheng Chen <sheche@microsoft.com>

Author: jdneo

README.md

@@ -214,6 +214,7 @@ The following settings are supported:
 New in 1.13.0
 * `java.compile.nullAnalysis.mode`: Specify how to enable the annotation-based null analysis. Supported values are `disabled` (disable the null analysis), `interactive` (asks when null annotation types are detected), `automatic` (automatically enable null analysis when null annotation types are detected). Defaults to `interactive`.
 * `java.cleanup.actionsOnSave`: The list of clean ups to be run on the current document when it's saved. Clean ups can automatically fix code style or programming mistakes. [Click here](document/_java.learnMoreAboutCleanUps.md#java-clean-ups) to learn more about what each clean up does.
+* `java.import.gradle.annotationProcessing.enabled`: Enable/disable the annotation processing on Gradle projects and delegate to JDT APT. Only works for Gradle 5.2 or higher.
 
 Semantic Highlighting
 ===============

package.json

@@ -328,6 +328,12 @@
           "description": "Setting for GRADLE_USER_HOME.",
           "scope": "window"
         },
+        "java.import.gradle.annotationProcessing.enabled": {
+          "type": "boolean",
+          "default": true,
+          "description": "Enable/disable the annotation processing on Gradle projects and delegate Annotation Processing to JDT APT. Only works for Gradle 5.2 or higher.",
+          "scope": "window"
+        },
         "java.maven.downloadSources": {
           "type": "boolean",
           "default": false,