Add toString to CoverageModel to verify Sonar coverage on new code

Temporary change to confirm JaCoCo coverage is properly imported by SonarCloud on PRs with Java changes.

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

Author: ThomasPerkins1123

core/src/main/java/com/diffblue/core/model/CoverageModel.java

@@ -47,4 +47,16 @@ public int getCoveredByDiffblueCount() {
   public void setCoveredByDiffblueCount(int coveredByDiffblueCount) {
     this.coveredByDiffblueCount = coveredByDiffblueCount;
   }
+
+  @Override
+  public String toString() {
+    return "CoverageModel{"
+        + "coverableLinesCount="
+        + coverableLinesCount
+        + ", coveredByDiffblueOnlyCount="
+        + coveredByDiffblueOnlyCount
+        + ", coveredByDiffblueCount="
+        + coveredByDiffblueCount
+        + '}';
+  }
 }

core/src/test/java/com/diffblue/core/CoverageModelBuilderTest.java

@@ -43,6 +43,7 @@ void testBuildPerFileCoverageModel() throws Exception {
     assertEquals(12, vetCoverageModel.getCoverableLinesCount());
     assertEquals(11, vetCoverageModel.getCoveredByDiffblueOnlyCount());
     assertEquals(12, vetCoverageModel.getCoveredByDiffblueCount());
+    assertTrue(vetCoverageModel.toString().contains("coverableLinesCount=12"));
 
     // check that the sum of all the file stats match the overall expected values
     assertEquals(