diff --git a/engine/src/main/java/org/camunda/bpm/engine/impl/cmd/CommandLogger.java b/engine/src/main/java/org/camunda/bpm/engine/impl/cmd/CommandLogger.java
index 4edffbf1951..6043d555423 100644
--- a/engine/src/main/java/org/camunda/bpm/engine/impl/cmd/CommandLogger.java
+++ b/engine/src/main/java/org/camunda/bpm/engine/impl/cmd/CommandLogger.java
@@ -358,7 +358,7 @@ public ProcessEngineException exceptionJobRetriesMustNotBeNegative(Integer retri
 
   public ProcessEngineException exceptionWhileRetrievingDiagnosticsDataRegistryNull() {
     return new ProcessEngineException(
-        exceptionMessage("019", "Error while retrieving diagnostics data. Diagnostics registry was not initialized."));
+        exceptionMessage("055", "Error while retrieving diagnostics data. Diagnostics registry was not initialized."));
   }
 
 }
diff --git a/engine/src/main/java/org/camunda/bpm/engine/impl/diagnostics/DiagnosticsCollector.java b/engine/src/main/java/org/camunda/bpm/engine/impl/diagnostics/DiagnosticsCollector.java
index 72209c807ea..eb13b86aa3b 100644
--- a/engine/src/main/java/org/camunda/bpm/engine/impl/diagnostics/DiagnosticsCollector.java
+++ b/engine/src/main/java/org/camunda/bpm/engine/impl/diagnostics/DiagnosticsCollector.java
@@ -22,7 +22,6 @@
 import static org.camunda.bpm.engine.management.Metrics.ROOT_PROCESS_INSTANCE_START;
 
 import java.util.HashMap;
-import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 import org.camunda.bpm.engine.impl.metrics.Meter;
@@ -38,14 +37,10 @@
 
 public class DiagnosticsCollector {
 
-  protected static final Set<String> METRICS_TO_REPORT = new HashSet<>();
-
-  static {
-    METRICS_TO_REPORT.add(ROOT_PROCESS_INSTANCE_START);
-    METRICS_TO_REPORT.add(EXECUTED_DECISION_INSTANCES);
-    METRICS_TO_REPORT.add(EXECUTED_DECISION_ELEMENTS);
-    METRICS_TO_REPORT.add(ACTIVTY_INSTANCE_START);
-  }
+  protected static final Set<String> METRICS_TO_REPORT = Set.of(ROOT_PROCESS_INSTANCE_START,
+                                                                EXECUTED_DECISION_INSTANCES,
+                                                                EXECUTED_DECISION_ELEMENTS,
+                                                                ACTIVTY_INSTANCE_START);
 
   protected TelemetryDataImpl staticData;
   protected DiagnosticsRegistry diagnosticsRegistry;
diff --git a/engine/src/main/java/org/camunda/bpm/engine/impl/util/ProcessEngineDetails.java b/engine/src/main/java/org/camunda/bpm/engine/impl/util/ProcessEngineDetails.java
index ca904094338..943eb716d83 100644
--- a/engine/src/main/java/org/camunda/bpm/engine/impl/util/ProcessEngineDetails.java
+++ b/engine/src/main/java/org/camunda/bpm/engine/impl/util/ProcessEngineDetails.java
@@ -18,7 +18,7 @@
 
 /**
  * Holds process engine version and edition (enterprise or community)
- * Used in retrieving the process engine details for diagnostic data
+ * Used in retrieving the process engine details for diagnostics data
  */
 public class ProcessEngineDetails {