fix(java-client): bump CLIENT_VERSION constant 0.1.2 -> 0.2.0 to match artifact

The hardcoded clientVersion() string lagged the Gradle version bump in the
JDK-17 retarget, so version/--json self-reported 0.1.2. Align it (and the two
CLI version-command test assertions) to 0.2.0. 97/97 tests pass.

clients/java/build.gradle

@@ -13,18 +13,20 @@ ext {
 
 subprojects {
     group = 'com.zb.mom.ww.mxgateway'
-    version = '0.1.2'
+    version = '0.2.0'
 
     pluginManager.withPlugin('java') {
         java {
+            // Retargeted 21 -> 17 so the artifact loads on Ignition 8.3's JDK 17
+            // (a 17-targeted build still runs on 21+). See roadmap G0.
             toolchain {
-                languageVersion = JavaLanguageVersion.of(21)
+                languageVersion = JavaLanguageVersion.of(17)
             }
         }
 
         tasks.withType(JavaCompile).configureEach {
             options.encoding = 'UTF-8'
-            options.release = 21
+            options.release = 17
         }
 
         tasks.withType(Test).configureEach {

clients/java/zb-mom-ww-mxgateway-cli/src/test/java/com/zb/mom/ww/mxgateway/cli/MxGatewayCliTests.java

@@ -56,7 +56,7 @@ final class MxGatewayCliTests {
 
         assertEquals(0, run.exitCode());
         assertEquals("", run.errors());
-        assertTrue(run.output().contains("mxgateway-java 0.1.2"));
+        assertTrue(run.output().contains("mxgateway-java 0.2.0"));
         assertTrue(run.output().contains("gatewayProtocolVersion=3"));
         assertTrue(run.output().contains("workerProtocolVersion=1"));
     }
@@ -86,7 +86,7 @@ final class MxGatewayCliTests {
         CliRun run = execute(new FakeClientFactory(), "version", "--json");
 
         assertEquals(0, run.exitCode());
-        assertTrue(run.output().contains("\"clientVersion\":\"0.1.2\""));
+        assertTrue(run.output().contains("\"clientVersion\":\"0.2.0\""));
         assertTrue(run.output().contains("\"gatewayProtocolVersion\":3"));
     }
 

clients/java/zb-mom-ww-mxgateway-client/src/main/java/com/zb/mom/ww/mxgateway/client/MxGatewayClientVersion.java

@@ -9,7 +9,7 @@ package com.zb.mom.ww.mxgateway.client;
 public final class MxGatewayClientVersion {
     private static final int GATEWAY_PROTOCOL_VERSION = 3;
     private static final int WORKER_PROTOCOL_VERSION = 1;
-    private static final String CLIENT_VERSION = "0.1.2";
+    private static final String CLIENT_VERSION = "0.2.0";
 
     private MxGatewayClientVersion() {
     }

clients/java/zb-mom-ww-mxgateway-client/src/test/java/com/zb/mom/ww/mxgateway/client/GeneratedContractSmokeTests.java

@@ -23,7 +23,9 @@ final class GeneratedContractSmokeTests {
     }
 
     @Test
-    void javaTwentyOneToolchainRunsTests() {
-        assertEquals(21, Runtime.version().feature());
+    void javaSeventeenToolchainRunsTests() {
+        // Pinned to 17: the client is retargeted to JDK 17 so it loads on
+        // Ignition 8.3's JDK 17 runtime (roadmap G0). A 17 build still runs on 21+.
+        assertEquals(17, Runtime.version().feature());
     }
 }