fix: restore Java 11/17 compatibility and add robust Makefile

- Use Grizzly 4.0.2 for Java 11/17 and 5.0.0 for Java 21+.
- Add Makefile for testing against all supported JDKs with version validation.
- Include JDK-specific Error Prone versions and flags for JDK 21+.

Author: bramp

Makefile

@@ -0,0 +1,62 @@
+JDK_VERSIONS := 11 17 21
+
+.PHONY: help
+help:
+	@echo "Usage:"
+	@echo "  make test         - Run full tests (clean verify) on all supported JDKs ($(JDK_VERSIONS))"
+	@echo "  make compile      - Run clean compile on all supported JDKs ($(JDK_VERSIONS))"
+	@echo "  make version      - Show current project version"
+	@echo "  make test-jdk-XX  - Run tests on a specific JDK version (e.g., make test-jdk-11)"
+
+.PHONY: version
+version:
+	@mvn help:evaluate -Dexpression=project.version -q -DforceStdout
+	@echo
+
+.PHONY: test
+test: $(addprefix test-jdk-,$(JDK_VERSIONS))
+
+.PHONY: compile
+compile: $(addprefix compile-jdk-,$(JDK_VERSIONS))
+
+test-jdk-%:
+	@echo "------------------------------------------------------------"
+	@echo "Testing with JDK $*..."
+	@actual_home=$$(/usr/libexec/java_home -v $* 2>/dev/null); \
+	actual_version=$$([ -n "$$actual_home" ] && "$$actual_home/bin/java" -XshowSettings:properties -version 2>&1 | grep "java.specification.version" | awk '{print $$3}' | tr -d '"'); \
+	if [ "$$actual_version" != "$*" ]; then \
+		brew_path=$$(brew --prefix openjdk@$* 2>/dev/null); \
+		if [ -n "$$brew_path" ] && [ -d "$$brew_path/libexec/openjdk.jdk/Contents/Home" ]; then \
+			actual_home="$$brew_path/libexec/openjdk.jdk/Contents/Home"; \
+			actual_version=$$("$$actual_home/bin/java" -XshowSettings:properties -version 2>&1 | grep "java.specification.version" | awk '{print $$3}' | tr -d '"'); \
+		fi; \
+	fi; \
+	if [ "$$actual_version" != "$*" ]; then \
+		echo "ERROR: JDK $* not found or not active."; \
+		echo "To install it, run: brew install openjdk@$*"; \
+		exit 1; \
+	fi; \
+	export JAVA_HOME="$$actual_home"; \
+	mvn -version; \
+	mvn clean verify -Dgpg.skip
+
+compile-jdk-%:
+	@echo "------------------------------------------------------------"
+	@echo "Compiling with JDK $*..."
+	@actual_home=$$(/usr/libexec/java_home -v $* 2>/dev/null); \
+	actual_version=$$([ -n "$$actual_home" ] && "$$actual_home/bin/java" -XshowSettings:properties -version 2>&1 | grep "java.specification.version" | awk '{print $$3}' | tr -d '"'); \
+	if [ "$$actual_version" != "$*" ]; then \
+		brew_path=$$(brew --prefix openjdk@$* 2>/dev/null); \
+		if [ -n "$$brew_path" ] && [ -d "$$brew_path/libexec/openjdk.jdk/Contents/Home" ]; then \
+			actual_home="$$brew_path/libexec/openjdk.jdk/Contents/Home"; \
+			actual_version=$$("$$actual_home/bin/java" -XshowSettings:properties -version 2>&1 | grep "java.specification.version" | awk '{print $$3}' | tr -d '"'); \
+		fi; \
+	fi; \
+	if [ "$$actual_version" != "$*" ]; then \
+		echo "ERROR: JDK $* not found or not active."; \
+		echo "To install it, run: brew install openjdk@$*"; \
+		exit 1; \
+	fi; \
+	export JAVA_HOME="$$actual_home"; \
+	mvn -version; \
+	mvn clean compile

pom.xml

@@ -127,7 +127,7 @@
             <dependency>
                 <groupId>org.glassfish.grizzly</groupId>
                 <artifactId>grizzly-http-server</artifactId>
-                <version>5.0.0</version>
+                <version>4.0.2</version>
             </dependency>
         </dependencies>
     </dependencyManagement>
@@ -836,6 +836,15 @@
             <properties>
                 <error.prone.version>2.48.0</error.prone.version>
             </properties>
+            <dependencyManagement>
+                <dependencies>
+                    <dependency>
+                        <groupId>org.glassfish.grizzly</groupId>
+                        <artifactId>grizzly-http-server</artifactId>
+                        <version>5.0.0</version>
+                    </dependency>
+                </dependencies>
+            </dependencyManagement>
             <build>
                 <pluginManagement>
                     <plugins>