diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index 7f93135..d64cd49 100644
Binary files a/gradle/wrapper/gradle-wrapper.jar and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 1af9e09..a80b22c 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,6 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.5-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.6-bin.zip
 networkTimeout=10000
 validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
diff --git a/optimiser-controller/src/main/java/eu/nebulouscloud/optimiser/controller/ExnConnector.java b/optimiser-controller/src/main/java/eu/nebulouscloud/optimiser/controller/ExnConnector.java
index b45bba0..b0eef82 100644
--- a/optimiser-controller/src/main/java/eu/nebulouscloud/optimiser/controller/ExnConnector.java
+++ b/optimiser-controller/src/main/java/eu/nebulouscloud/optimiser/controller/ExnConnector.java
@@ -114,8 +114,8 @@ public class ExnConnector {
      * Connect to ActiveMQ and activate all publishers and consumers.  It is
      * an error to start the controller more than once.
      *
-     * @param synchronizer if non-null, a countdown latch that will be signaled
-     *  when the connector is stopped by calling {@link
+     * @param synchronizer if non-null, a countdown latch that will be
+     *  signaled when the connector is stopped by calling {@link
      *  CountDownLatch#countDown} once.
      */
     public synchronized void start(CountDownLatch synchronizer) {
diff --git a/optimiser-controller/src/main/java/eu/nebulouscloud/optimiser/controller/SalConnector.java b/optimiser-controller/src/main/java/eu/nebulouscloud/optimiser/controller/SalConnector.java
index 8978313..2e57daf 100644
--- a/optimiser-controller/src/main/java/eu/nebulouscloud/optimiser/controller/SalConnector.java
+++ b/optimiser-controller/src/main/java/eu/nebulouscloud/optimiser/controller/SalConnector.java
@@ -26,15 +26,23 @@ public class SalConnector {
 
     private static final ObjectMapper mapper = new ObjectMapper();
 
+    /**
+     * Get list of node candidates that fulfil the requirements.
+     *
+     * See https://github.com/ow2-proactive/scheduling-abstraction-layer/blob/master/documentation/nodecandidates-endpoints.md#71--filter-node-candidates-endpoint
+     *
+     * @param requirements The list of requirements.
+     * @param appID The application ID, if available.
+     * @return A list of node candidates, or null in case of error.
+     */
     public static List<NodeCandidate> findNodeCandidates(List<Requirement> requirements, String appID) {
-        Map<String, Object> msg = new HashMap<>();
-        Map<String, Object> metadata = new HashMap<>();
-        metadata.put("user", "admin");
-        msg.put("metaData", metadata);
+        Map<String, Object> msg;
         try {
-	    msg.put("body", mapper.writeValueAsString(requirements));
+            msg = Map.of(
+                "metaData", Map.of("user", "admin"),
+                "body", mapper.writeValueAsString(requirements));
 	} catch (JsonProcessingException e) {
-            log.error("Could not convert requirements list to JSON string", e);
+            log.error("Could not convert requirements list to JSON string (this should never happen)", e);
             return null;
 	}
         Map<String, Object> response = ExnConnector.findNodeCandidates.sendSync(msg, appID, null, false);
@@ -42,7 +50,7 @@ public class SalConnector {
 	try {
 	    return Arrays.asList(mapper.readValue(body, NodeCandidate[].class));
 	} catch (JsonProcessingException e) {
-            log.error("Error receiving findNodeCandidates result", e);
+            log.error("Error receiving findNodeCandidates result (this should never happen)", e);
             return null;
 	}
     }