fix: switch to JUnit Jupiter, remove unused mockito, fix SpotBugs errors

- Remove mockito-core (unused) and workflow-step-api test classifier
- Add junit-jupiter (BOM-managed) for JUnit 5
- Migrate ForgeAIPluginTest from JUnit 4 to JUnit Jupiter
- Fix RCN_REDUNDANT_NULLCHECK in healthCheck() across all providers
- Suppress VA_FORMAT_STRING_USES_NEWLINE in ForgeAIReportGenerator
  (HTML output intentionally uses \n, not platform-dependent %n)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: saurabh-oss

pom.xml

@@ -104,15 +104,8 @@
 
         <!-- Test Dependencies -->
         <dependency>
-            <groupId>org.jenkins-ci.plugins.workflow</groupId>
-            <artifactId>workflow-step-api</artifactId>
-            <classifier>tests</classifier>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.mockito</groupId>
-            <artifactId>mockito-core</artifactId>
-            <version>5.11.0</version>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
             <scope>test</scope>
         </dependency>
     </dependencies>

src/main/java/io/forgeai/jenkins/llm/AnthropicProvider.java

@@ -86,7 +86,8 @@ public String complete(String systemPrompt, String userPrompt, int maxTokens) th
     @Override
     public boolean healthCheck() {
         try {
-            return complete("You are a health-check bot.", "Reply OK", 10) != null;
+            complete("You are a health-check bot.", "Reply OK", 10);
+            return true;
         } catch (LLMException e) {
             return false;
         }

src/main/java/io/forgeai/jenkins/llm/OpenAICompatibleProvider.java

@@ -87,7 +87,8 @@ public String complete(String systemPrompt, String userPrompt, int maxTokens) th
     @Override
     public boolean healthCheck() {
         try {
-            return complete("You are a health-check bot.", "Reply OK", 10) != null;
+            complete("You are a health-check bot.", "Reply OK", 10);
+            return true;
         } catch (LLMException e) {
             return false;
         }

src/main/java/io/forgeai/jenkins/reports/ForgeAIReportGenerator.java

@@ -1,5 +1,6 @@
 package io.forgeai.jenkins.reports;
 
+import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
 import java.text.SimpleDateFormat;
 import java.util.Date;
 import java.util.List;
@@ -12,6 +13,8 @@ public final class ForgeAIReportGenerator {
 
     private ForgeAIReportGenerator() {}
 
+    @SuppressFBWarnings(value = "VA_FORMAT_STRING_USES_NEWLINE",
+            justification = "HTML output intentionally uses \\n, not platform-dependent %n")
     public static String generateHtml(List<AnalysisResult> results, String projectName,
                                        String buildNumber) {
         StringBuilder html = new StringBuilder();

src/test/java/io/forgeai/jenkins/ForgeAIPluginTest.java

@@ -2,18 +2,18 @@
 
 import io.forgeai.jenkins.analyzers.ResultParser;
 import io.forgeai.jenkins.reports.AnalysisResult;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 import java.io.PrintStream;
 
-import static org.junit.Assert.*;
+import static org.junit.jupiter.api.Assertions.*;
 
-public class ForgeAIPluginTest {
+class ForgeAIPluginTest {
 
     private final PrintStream log = System.out;
 
     @Test
-    public void testResultParser_validJson() {
+    void testResultParser_validJson() {
         String json = """
                 {
                   "score": 7,
@@ -40,7 +40,7 @@ public void testResultParser_validJson() {
     }
 
     @Test
-    public void testResultParser_markdownWrapped() {
+    void testResultParser_markdownWrapped() {
         String json = """
                 ```json
                 {"score":9,"severity":"LOW","summary":"All good.","findings":[]}
@@ -52,15 +52,15 @@ public void testResultParser_markdownWrapped() {
     }
 
     @Test
-    public void testResultParser_malformedJson() {
+    void testResultParser_malformedJson() {
         String garbage = "This is not JSON at all.";
         AnalysisResult result = ResultParser.parse(garbage, "test", "Test", log);
-        assertEquals(5, result.getScore()); // default fallback
+        assertEquals(5, result.getScore());
         assertNotNull(result.getRawMarkdown());
     }
 
     @Test
-    public void testResultParser_extraTextBeforeJson() {
+    void testResultParser_extraTextBeforeJson() {
         String response = "Sure! Here is the analysis:\n{\"score\":4,\"severity\":\"HIGH\"," +
                 "\"summary\":\"Issues found.\",\"findings\":[]}";
         AnalysisResult result = ResultParser.parse(response, "vuln", "Vuln", log);
@@ -69,7 +69,7 @@ public void testResultParser_extraTextBeforeJson() {
     }
 
     @Test
-    public void testAnalysisResult_countBySeverity() {
+    void testAnalysisResult_countBySeverity() {
         AnalysisResult r = new AnalysisResult("test", "Test");
         r.addFinding(new AnalysisResult.Finding("A", "CRITICAL", "desc"));
         r.addFinding(new AnalysisResult.Finding("B", "CRITICAL", "desc"));
@@ -82,7 +82,7 @@ public void testAnalysisResult_countBySeverity() {
     }
 
     @Test
-    public void testAnalysisResult_scoreClamp() {
+    void testAnalysisResult_scoreClamp() {
         AnalysisResult r = new AnalysisResult("test", "Test");
         r.setScore(15);
         assertEquals(10, r.getScore());