search all installed JDKs when java.home not specified (#1701)

Signed-off-by: Yan Zhang <yanzh@microsoft.com>

Author: Eskibear

README.md

@@ -51,15 +51,16 @@ See the [changelog](CHANGELOG.md) for the latest release. You might also find us
 
 Setting the JDK
 ===============
-The path to the Java Development Kit is searched in the following order:
+## Java Tooling JDK
+This JDK will be used to launch the Java Language Server. And by default, will also be used to compile your projects.
+
+The path to the Java Development Kit can be specified by the `java.home` setting in VS Code settings (workspace/user settings). If not specified, it is searched in the following order until a JDK meets current minimum requirement.
 
-- the `java.home` setting in VS Code settings (workspace then user settings)
 - the `JDK_HOME` environment variable
 - the `JAVA_HOME` environment variable
 - on the current system path
 
-This JDK will be used to launch the Java Language Server. And by default, will be used to compile your projects.
-
+## Project JDKs
 If you need to compile your projects against a different JDK version, it's recommended you configure the `java.configuration.runtimes` property in your user settings, eg:
 
 ```json

package-lock.json

@@ -880,6 +880,7 @@
     "@types/mocha": "^5.2.5",
     "@types/node": "^8.10.51",
     "@types/vscode": "^1.47.0",
+    "@types/winreg": "^1.2.30",
     "@types/winston": "^2.4.4",
     "gulp": "^4.0.2",
     "gulp-decompress": "^3.0.0",
@@ -903,6 +904,7 @@
     "fs-extra": "^8.1.0",
     "glob": "^7.1.3",
     "vscode-languageclient": "6.0.0-next.9",
+    "winreg-utf8": "^0.1.1",
     "winston": "^3.2.1",
     "winston-daily-rotate-file": "^3.10.0"
   }