Send total coverage back to GitLab instead of new coverage

The coverage send back via the GitLab API should be the total coverage
of the project, not the coverage of the new code in the PR. The GitLab
docs explicitly mention this:
https://docs.gitlab.com/ee/api/commits.html#post-the-build-status-to-a-commit

The coverage reported by decorating the PR via a comment is not affected;
this still shows both the total and new coverage.

Note that there is an open GitLab issue for natively displaying new coverage
for just the diff of a PR (https://gitlab.com/gitlab-org/gitlab/-/issues/20895),
but this is not yet implemented.

In addition, reporting coverage back is optional. So if there is no coverage
information, we do not report it back.

src/main/java/com/github/mc1arke/sonarqube/plugin/ce/pullrequest/AnalysisDetails.java

@@ -147,9 +147,7 @@ public Optional<String> getScannerProperty(String propertyName) {
     public String createAnalysisSummary(FormatterFactory formatterFactory) {
 
         BigDecimal newCoverage = getNewCoverage().orElse(null);
-
-
-        double coverage = findMeasure(CoreMetrics.COVERAGE_KEY).map(Measure::getDoubleValue).orElse(0D);
+        BigDecimal coverage = getCoverage().orElse(null);
 
         BigDecimal newDuplications = findQualityGateCondition(CoreMetrics.NEW_DUPLICATED_LINES_DENSITY_KEY)
                 .filter(condition -> condition.getStatus() != EvaluationStatus.NO_VALUE)
@@ -373,6 +371,10 @@ public Optional<BigDecimal> getNewCoverage(){
                 .map(BigDecimal::new);
     }
 
+    public Optional<BigDecimal> getCoverage(){
+        return findMeasure(CoreMetrics.COVERAGE_KEY).map(Measure::getDoubleValue).map(BigDecimal::new);
+    }
+
     public static class BranchDetails {
 
         private final String branchName;

src/main/java/com/github/mc1arke/sonarqube/plugin/ce/pullrequest/gitlab/GitlabServerPullRequestDecorator.java

@@ -169,7 +169,7 @@ public DecorationResult decorateQualityGateStatus(AnalysisDetails analysis, AlmS
             List<NameValuePair> summaryContentParams = Collections
                     .singletonList(new BasicNameValuePair("body", summaryComment));
 
-            String coverageValue = analysis.getNewCoverage().orElse(BigDecimal.ZERO).toString();
+            BigDecimal coverageValue = analysis.getCoverage().orElse(null);
 
             postStatus(new StringBuilder(statusUrl), headers, analysis, coverageValue);
 
@@ -315,7 +315,7 @@ private void postCommitComment(String commitCommentUrl, Map<String, String> head
     }
 
     private void postStatus(StringBuilder statusPostUrl, Map<String, String> headers, AnalysisDetails analysis,
-                            String coverage) throws IOException {
+                            BigDecimal coverage) throws IOException {
         //See https://docs.gitlab.com/ee/api/commits.html#post-the-build-status-to-a-commit
         statusPostUrl.append("?name=SonarQube");
         String status = (analysis.getQualityGateStatus() == QualityGate.Status.OK ? "success" : "failed");
@@ -326,7 +326,9 @@ private void postStatus(StringBuilder statusPostUrl, Map<String, String> headers
                         .encode(analysis.getBranchName(),
                                 StandardCharsets.UTF_8.name())), StandardCharsets.UTF_8.name()));
         statusPostUrl.append("&description=").append(URLEncoder.encode("SonarQube Status", StandardCharsets.UTF_8.name()));
-        statusPostUrl.append("&coverage=").append(coverage);
+        if (coverage != null) {
+            statusPostUrl.append("&coverage=").append(coverage.toString());
+        }
         analysis.getScannerProperty(PULLREQUEST_GITLAB_PIPELINE_ID).ifPresent(pipelineId -> statusPostUrl.append("&pipeline_id=").append(pipelineId));
 
         HttpPost httpPost = new HttpPost(statusPostUrl.toString());

src/test/java/com/github/mc1arke/sonarqube/plugin/ce/pullrequest/gitlab/GitlabServerPullRequestDecoratorTest.java

@@ -85,7 +85,7 @@ public void decorateQualityGateStatus() {
         when(analysisDetails.getAnalysisProjectKey()).thenReturn(projectKey);
         when(analysisDetails.getBranchName()).thenReturn(branchName);
         when(analysisDetails.getCommitSha()).thenReturn(commitSHA);
-        when(analysisDetails.getNewCoverage()).thenReturn(Optional.of(BigDecimal.TEN));
+        when(analysisDetails.getCoverage()).thenReturn(Optional.of(BigDecimal.TEN));
         PostAnalysisIssueVisitor issueVisitor = mock(PostAnalysisIssueVisitor.class);
         PostAnalysisIssueVisitor.ComponentIssue componentIssue = mock(PostAnalysisIssueVisitor.ComponentIssue.class);
         PostAnalysisIssueVisitor.LightIssue defaultIssue = mock(PostAnalysisIssueVisitor.LightIssue.class);