diff --git a/packages/http-client-java/CONTRIBUTING.md b/packages/http-client-java/CONTRIBUTING.md
new file mode 100644
index 00000000000..adcfe07f451
--- /dev/null
+++ b/packages/http-client-java/CONTRIBUTING.md
@@ -0,0 +1,70 @@
+# Contributing to TypeSpec Java Emitter Library
+
+## Prerequisite
+
+Install [Node.js](https://nodejs.org/) 20 or above. (Verify by running `node --version`)
+
+Install [Java](https://docs.microsoft.com/java/openjdk/download) 17 or above. (Verify by running `java --version`)
+
+Install [Maven](https://maven.apache.org/download.cgi). (Verify by running `mvn --version`)
+
+## Project Structure
+
+The TypeSpec Java Emitter Library is a Node.js package.
+It publishes to [npm `@typespec/http-client-java`](https://www.npmjs.com/package/@typespec/http-client-java).
+
+As a Node.js package, the entry of the library is written in TypeScript, under `emitter` folder.
+
+As a Java code generator, part of the implementation is written in Java, under `generator` folder.
+Java code is packaged into a JAR file, and included in the Node.js package. The JAR file is called at runtime by TypeScript code.
+
+## Build and Pack
+
+["Setup.ps1" script](https://github.com/microsoft/typespec/blob/main/packages/http-client-java/Setup.ps1) builds TypeScript code and Java code, and packs them into "typespec-http-client-java-[version].tgz".
+
+One can use npm to install the `@typespec/http-client-java` tgz locally.
+
+```
+npm install [path-to-typespec-http-client-java-tgz]
+```
+
+## End-to-end Tests
+
+There is 2 end-to-end test modules:
+
+- `packages/http-client-java/generator/http-client-generator-clientcore-test` for testing of unbranded code
+- `packages/http-client-java/generator/http-client-generator-test` for testing of branded code
+
+Their folder structure is identical. In the following sub-sections, the script or command should be invoked in one of the two folders.
+
+### Set-up the environment
+
+["Setup.ps1" script in test module](https://github.com/microsoft/typespec/blob/main/packages/http-client-java/generator/http-client-generator-clientcore-test/Setup.ps1) builds the emitter, and sets up the test environment.
+
+Internally, it does
+
+1. Build the `@typespec/http-client-java` tgz locally. See [Build and Pack](#build-and-pack).
+2. Re-install the tgz (along with other dependencies) in the test module.
+
+### Generate the test code
+
+If the feature or bug fix involves code change on generated code, you will need to re-generate the test code in one or both of the test modules.
+
+["Generate.ps1" script](https://github.com/microsoft/typespec/blob/main/packages/http-client-java/generator/http-client-generator-clientcore-test/Generate.ps1) (internally it calls the "Setup.ps1" script) generates the code for end-to-end testing.
+The code is generated from TypeSpec source from [npm `@typespec/http-specs` package](https://www.npmjs.com/package/@typespec/http-specs).
+
+### Run the end-to-end tests
+
+["Spector-Tests.ps1" script](https://github.com/microsoft/typespec/blob/main/packages/http-client-java/generator/http-client-generator-clientcore-test/Spector-Tests.ps1) starts the spector server, and run all the Java tests.
+
+When writing / updating Java tests, you can manually
+
+1. Start the test server with `npm run spector-serve` (or `npm run spector-start` to start as a background process, `npm run spector-stop` to stop).
+2. Run the Java tests in the module.
+
+## Format Code
+
+Before creating pull request, the code is required to be well-formatted.
+
+Run `npm run format` in "packages/http-client-java" folder.
+It formats TypeScript code as well as Java code.
diff --git a/packages/http-client-java/Setup.ps1 b/packages/http-client-java/Setup.ps1
index fe128f20cbb..9d9e3c0ae70 100644
--- a/packages/http-client-java/Setup.ps1
+++ b/packages/http-client-java/Setup.ps1
@@ -1,4 +1,4 @@
 # re-build http-client-java
-npm install 
+npm ci 
 npm run clean && npm run build
 npm pack
diff --git a/packages/http-client-java/package.json b/packages/http-client-java/package.json
index 6f3cfd6e5c0..d4bf8c20ad4 100644
--- a/packages/http-client-java/package.json
+++ b/packages/http-client-java/package.json
@@ -29,7 +29,7 @@
     "build": "npm run build:generator && npm run build:emitter",
     "build:emitter": "tsc -p ./emitter/tsconfig.build.json",
     "build:generator": "mvn clean install --no-transfer-progress -T 1C -f ./generator/pom.xml",
-    "format": "pnpm -w format:dir packages/http-client-java",
+    "format": "pnpm -w format:dir packages/http-client-java && mvn spotless:apply --no-transfer-progress -T 1C --activate-profiles test -f ./generator/pom.xml",
     "lint": "eslint . --max-warnings=0",
     "lint:fix": "eslint . --fix",
     "watch": "tsc -p ./emitter/tsconfig.build.json --watch",