Update to the latest Java JDK 16 (#886)

Signed-off-by: Jinbo Wang <jinbwan@microsoft.com>

containers/java/.devcontainer/Dockerfile

@@ -1,4 +1,4 @@
-# [Choice] Java version: 11, 15
+# [Choice] Java version: 11, 16
 ARG VARIANT=11
 FROM mcr.microsoft.com/vscode/devcontainers/java:${VARIANT}
 

containers/java/.devcontainer/base.Dockerfile

@@ -1,4 +1,4 @@
-# [Choice] Java version: 11, 15
+# [Choice] Java version: 11, 16
 ARG VARIANT=11
 FROM openjdk:${VARIANT}-jdk-buster
 

containers/java/.devcontainer/devcontainer.json

@@ -3,7 +3,7 @@
 	"build": {
 		"dockerfile": "Dockerfile",
 		"args": {
-			// Update the VARIANT arg to pick a Java version: 11, 15
+			// Update the VARIANT arg to pick a Java version: 11, 16
 			"VARIANT": "11",
 			// Options
 			"INSTALL_MAVEN": "false",

containers/java/README.md

@@ -10,7 +10,7 @@
 | *Categories* | Core, Languages |
 | *Definition type* | Dockerfile |
 | *Published images* | mcr.microsoft.com/vscode/devcontainers/java |
-| *Available image variants* | 11, 15 ([full list](https://mcr.microsoft.com/v2/vscode/devcontainers/java/tags/list)) |
+| *Available image variants* | 11, 16 ([full list](https://mcr.microsoft.com/v2/vscode/devcontainers/java/tags/list)) |
 | *Published image architecture(s)* | x86-64 |
 | *Works in Codespaces* | Yes |
 | *Container host OS support* | Linux, macOS, Windows |
@@ -26,14 +26,14 @@ See **[history](history)** for information on the contents of published images.
 While this definition should work unmodified, you can select the version of Java the container uses by updating the `VARIANT` arg in the included `devcontainer.json` (and rebuilding if you've already created the container).
 
 ```json
-"args": { "VARIANT": "15" }
+"args": { "VARIANT": "16" }
 ```
 
 You can also directly reference pre-built versions of `.devcontainer/base.Dockerfile` by using the `image` property in `.devcontainer/devcontainer.json` or updating the `FROM` statement in your own  `Dockerfile` to one of the following. An example `Dockerfile` is included in this repository.
 
 - `mcr.microsoft.com/vscode/devcontainers/java` (latest)
 - `mcr.microsoft.com/vscode/devcontainers/java:11`
-- `mcr.microsoft.com/vscode/devcontainers/java:15`
+- `mcr.microsoft.com/vscode/devcontainers/java:16`
 
 You can decide how often you want updates by referencing a [semantic version](https://semver.org/) of each image. For example:
 

containers/java/definition-manifest.json

@@ -1,5 +1,5 @@
 {
-	"variants": [ "15", "11" ],
+	"variants": [ "16", "11" ],
 	"definitionVersion": "0.201.6",
 	"build": {
 		"latest": true,