add devcontainer config

.devcontainer/Dockerfile

@@ -0,0 +1,25 @@
+# See here for image contents: https://github.com/microsoft/vscode-dev-containers/tree/v0.222.0/containers/java/.devcontainer/base.Dockerfile
+
+# [Choice] Java version (use -bullseye variants on local arm64/Apple Silicon): 11, 17, 11-bullseye, 17-bullseye, 11-buster, 17-buster
+ARG VARIANT="17-bullseye"
+FROM mcr.microsoft.com/vscode/devcontainers/java:0-${VARIANT}
+
+# [Option] Install Maven
+ARG INSTALL_MAVEN="false"
+ARG MAVEN_VERSION=""
+# [Option] Install Gradle
+ARG INSTALL_GRADLE="false"
+ARG GRADLE_VERSION=""
+RUN if [ "${INSTALL_MAVEN}" = "true" ]; then su vscode -c "umask 0002 && . /usr/local/sdkman/bin/sdkman-init.sh && sdk install maven \"${MAVEN_VERSION}\""; fi \
+    && if [ "${INSTALL_GRADLE}" = "true" ]; then su vscode -c "umask 0002 && . /usr/local/sdkman/bin/sdkman-init.sh && sdk install gradle \"${GRADLE_VERSION}\""; fi
+
+# [Choice] Node.js version: none, lts/*, 16, 14, 12, 10
+ARG NODE_VERSION="none"
+RUN if [ "${NODE_VERSION}" != "none" ]; then su vscode -c "umask 0002 && . /usr/local/share/nvm/nvm.sh && nvm install ${NODE_VERSION} 2>&1"; fi
+
+# [Optional] Uncomment this section to install additional OS packages.
+# RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
+#     && apt-get -y install --no-install-recommends <your-package-list-here>
+
+# [Optional] Uncomment this line to install global node packages.
+# RUN su vscode -c "source /usr/local/share/nvm/nvm.sh && npm install -g <your-package-here>" 2>&1

.devcontainer/devcontainer.json

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+// For format details, see https://aka.ms/devcontainer.json. For config options, see the README at:
+// https://github.com/microsoft/vscode-dev-containers/tree/v0.222.0/containers/java
+{
+	"name": "Java",
+	"build": {
+		"dockerfile": "Dockerfile",
+		"args": {
+			// Update the VARIANT arg to pick a Java version: 11, 17
+			// Append -bullseye or -buster to pin to an OS version.
+			// Use the -bullseye variants on local arm64/Apple Silicon.
+			"VARIANT": "17",
+			// Options
+			"INSTALL_MAVEN": "true",
+			"INSTALL_GRADLE": "false",
+			"NODE_VERSION": "lts/*"
+		}
+	},
+
+	// Set *default* container specific settings.json values on container create.
+	"settings": { 
+		"java.home": "/docker-java-home"
+	},
+
+	// Add the IDs of extensions you want installed when the container is created.
+	"extensions": [
+		"vscjava.vscode-java-pack"
+	],
+
+	// Use 'forwardPorts' to make a list of ports inside the container available locally.
+	// "forwardPorts": [],
+
+	// Use 'postCreateCommand' to run commands after the container is created.
+	// "postCreateCommand": "java -version",
+
+	// Comment out to connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.
+	"remoteUser": "vscode"
+}