Standardize Java 25 setup and documentation (#379)

* Update documentation and add devcontainer for Java 25

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: thomasturrell <1552612+thomasturrell@users.noreply.github.com>

Author: Copilot

.devcontainer/devcontainer.json

@@ -0,0 +1,37 @@
+{
+  "name": "xAPI Java Development",
+  "image": "mcr.microsoft.com/devcontainers/java:1-25-bookworm",
+  
+  "features": {
+    "ghcr.io/devcontainers/features/java:1": {
+      "version": "25",
+      "jdkDistro": "tem",
+      "installMaven": "true"
+    }
+  },
+
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "vscjava.vscode-java-pack",
+        "vscjava.vscode-maven",
+        "redhat.java",
+        "vscjava.vscode-java-debug",
+        "vscjava.vscode-java-test",
+        "vscjava.vscode-spring-boot-dashboard",
+        "pivotal.vscode-spring-boot"
+      ],
+      "settings": {
+        "java.configuration.runtimes": [
+          {
+            "name": "JavaSE-25",
+            "path": "/usr/local/sdkman/candidates/java/current"
+          }
+        ],
+        "java.jdt.ls.java.home": "/usr/local/sdkman/candidates/java/current"
+      }
+    }
+  },
+
+  "remoteUser": "vscode"
+}

.github/copilot-instructions.md

@@ -11,7 +11,7 @@ xAPI Java is a library that helps you create applications that send or receive x
 
 ## Technology Stack
 
-- **Language**: Java 17 or newer (required)
+- **Language**: Java 25 or newer (required)
 - **Build Tool**: Maven (using Maven Wrapper `./mvnw`)
 - **Framework**: Spring Boot 3.5.7, Spring WebClient (reactive)
 - **Code Style**: Google Java Style Guide enforced via CheckStyle
@@ -20,6 +20,28 @@ xAPI Java is a library that helps you create applications that send or receive x
 - **Validation**: Jakarta Bean Validation
 - **Serialization**: Jackson (with custom modules for strict xAPI compliance)
 
+## Environment Setup
+
+### Java Installation with SDKMAN
+
+This project requires Java 25. We recommend using [SDKMAN!](https://sdkman.io/) to manage Java versions:
+
+```bash
+# Install SDKMAN (if not already installed)
+curl -s "https://get.sdkman.io" | bash
+
+# Install Java 25 (Temurin distribution recommended)
+sdk install java 25.0.1-tem
+
+# Set as default (optional)
+sdk default java 25.0.1-tem
+
+# Verify installation
+java -version
+```
+
+**Note**: The exact identifier (e.g., `25.0.1-tem`) may vary by platform and availability. Use `sdk list java` to see available Java 25 versions for your system.
+
 ## Building and Testing
 
 ### Build Commands

README.md

@@ -10,7 +10,24 @@ Both the xAPI Client and xAPI Model use a [fluent interface](https://en.wikipedi
 
 ## Requirements
 
-xAPI Java requires Java 17 or newer.
+xAPI Java requires Java 25 or newer.
+
+### Installing Java 25
+
+We recommend using [SDKMAN!](https://sdkman.io/) to install and manage Java versions:
+
+```bash
+# Install SDKMAN (if not already installed)
+curl -s "https://get.sdkman.io" | bash
+
+# Install Java 25 (Temurin distribution recommended)
+sdk install java 25.0.1-tem
+
+# Verify installation
+java -version
+```
+
+**Note**: The exact identifier (e.g., `25.0.1-tem`) may vary by platform and availability. Run `sdk list java` to see available Java 25 versions for your system and choose the appropriate one for your platform.
 
 ## xAPI Java Client