Add getNodeTokens method to ResourceManager

 - additionally, check that provided tokens is not null or empty, as null tokens causes deep issues in the rm database and core.

rm/rm-client/src/main/java/org/ow2/proactive/resourcemanager/common/util/RMProxyUserInterface.java

@@ -487,4 +487,9 @@ public class RMProxyUserInterface extends RMListenerProxy implements ResourceMan
     public void setNodeTokens(String nodeUrl, List<String> tokens) throws RMException {
         target.setNodeTokens(nodeUrl, tokens);
     }
+
+    @Override
+    public List<String> getNodeTokens(String nodeUrl) throws RMException {
+        return target.getNodeTokens(nodeUrl);
+    }
 }

rm/rm-client/src/main/java/org/ow2/proactive/resourcemanager/frontend/ResourceManager.java

@@ -572,4 +572,6 @@ public interface ResourceManager {
 
     void setNodeTokens(String nodeUrl, List<String> tokens) throws RMException;
 
+    List<String> getNodeTokens(String nodeUrl) throws RMException;
+
 }

rm/rm-server/src/main/java/org/ow2/proactive/resourcemanager/core/RMCore.java

@@ -3109,6 +3109,9 @@ public class RMCore implements ResourceManager, InitActive, RunActive {
 
     @Override
     public void addNodeToken(String nodeUrl, String token) throws RMException {
+        if (token == null || token.isEmpty()) {
+            throw new RMException("Invalid empty token");
+        }
         if (allNodes.containsKey(nodeUrl)) {
             RMNode rmNode = allNodes.get(nodeUrl);
             checkNodeAdminPermission(rmNode, caller);
@@ -3124,8 +3127,20 @@ public class RMCore implements ResourceManager, InitActive, RunActive {
         }
     }
 
+    public List<String> getNodeTokens(String nodeUrl) throws RMException {
+        if (allNodes.containsKey(nodeUrl)) {
+            RMNode rmNode = allNodes.get(nodeUrl);
+            return rmNode.getNodeTokens();
+        } else {
+            throw new RMException("Unknown node " + nodeUrl);
+        }
+    }
+
     @Override
     public void removeNodeToken(String nodeUrl, String token) throws RMException {
+        if (token == null || token.isEmpty()) {
+            throw new RMException("Invalid empty token");
+        }
         if (allNodes.containsKey(nodeUrl)) {
             RMNode rmNode = allNodes.get(nodeUrl);
             checkNodeAdminPermission(rmNode, caller);
@@ -3144,6 +3159,9 @@ public class RMCore implements ResourceManager, InitActive, RunActive {
 
     @Override
     public void setNodeTokens(String nodeUrl, List<String> tokens) throws RMException {
+        if (tokens.stream().anyMatch(token -> token == null || token.isEmpty())) {
+            throw new RMException("Invalid empty token in list " + tokens);
+        }
         if (allNodes.containsKey(nodeUrl)) {
             RMNode rmNode = allNodes.get(nodeUrl);
             rmNode.setNodeTokens(nodeUrl, tokens);