SONAR-16039 added new metric analysis_from_sonarqube_9_4

sonar-plugin-api/src/main/java/org/sonar/api/measures/CoreMetrics.java

 import java.util.NoSuchElementException;
 import org.sonar.api.utils.SonarException;
 
+import static org.sonar.api.measures.Metric.ValueType.BOOL;
+
 /**
  * @since 1.10
  */
     .setHidden(true)
     .create();
 
+  /**
+   * @since 9.4
+   */
+  public static final String ANALYSIS_FROM_SONARQUBE_9_4_KEY = "analysis_from_sonarqube_9_4";
+
+  /**
+   * @since 9.4
+   *
+   * This hidden metric that is only needed to fully fix the issue with identifying new issues when using reference branch
+   * that was haunting us in 9.3 and before. More details in the ticket SONAR-16039
+   */
+  public static final Metric<Integer> ANALYSIS_FROM_SONARQUBE_9_4 = new Metric.Builder(ANALYSIS_FROM_SONARQUBE_9_4_KEY,
+    "Analysis From SonarQube 9.4", BOOL)
+    .setDescription("Indicates whether the analysis has been run after the upgrade to SonarQube 9.4. It affects how the issues " +
+      "will be detected for branches that use reference branch as the strategy for detecting new code.")
+    .setDomain(CoreMetrics.DOMAIN_ISSUES)
+    .setHidden(true)
+    .create();
+
   private static final List<Metric> METRICS;
 
   static {

sonar-plugin-api/src/main/java/org/sonar/api/measures/Metric.java

     }
 
     /**
-     * Sets whether the metric should be hidden in Web UI (e.g. in Time Machine). Default is false.
+     * Sets whether the metric should be hidden in Web UI. Default is false.
      *
      * @param b true if the metric should be hidden.
      * @return the builder

sonar-plugin-api/src/test/java/org/sonar/api/resources/CoreMetricsTest.java

     assertThatThrownBy(() -> getMetric("unknown"))
       .isInstanceOf(NoSuchElementException.class);
   }
+
+  @Test
+  public void someMetricsAreMeantToBeHidden() {
+    Metric metric = getMetric("analysis_from_sonarqube_9_4");
+    assertThat(metric.isHidden()).isTrue();
+  }
 }