Introduce a helper method: OneDriveToken.isAssigned

src/main/java/org/jenkinsci/plugins/publishoveronedrive/OneDriveToken.java

@@ -43,6 +43,8 @@ public interface OneDriveToken extends StandardCredentials {
     @Nonnull
     String getClientId();
 
+    boolean isAssigned();
+
     @Nonnull
     String getClientSecret();
 

src/main/java/org/jenkinsci/plugins/publishoveronedrive/domain/OneDriveClient.java

@@ -65,10 +65,10 @@ public class OneDriveClient extends BPDefaultClient<OneDriveTransfer> {
 
     public boolean setClientIdAndSecret() throws IOException, OneDriveException {
         List<OneDriveToken> credentials = CredentialsProvider.lookupCredentials(OneDriveToken.class, Jenkins.getInstance(), null, (DomainRequirement) null);
-        for (OneDriveToken token : credentials) {
-            if (!token.getClientId().equals("") && !token.getClientSecret().equals("")) {
-                Config.CLIENT_ID = token.getClientId();
-                Config.CLIENT_SECRET = token.getClientSecret();
+        for (OneDriveToken t : credentials) {
+            if (t.isAssigned()) {
+                Config.CLIENT_ID = t.getClientId();
+                Config.CLIENT_SECRET = t.getClientSecret();
                 return true;
             }
         }
@@ -119,7 +119,7 @@ public class OneDriveClient extends BPDefaultClient<OneDriveTransfer> {
     }
 
     public boolean connect() throws OneDriveException, IOException {
-        setClientIdAndSecret();
+        this.setClientIdAndSecret();
         try {
             return onedrive.connect();
         } catch (IOException ioe) {

src/main/java/org/jenkinsci/plugins/publishoveronedrive/impl/OneDriveTokenImpl.java

@@ -85,6 +85,10 @@ public class OneDriveTokenImpl extends BaseStandardCredentials implements OneDri
         return accessCode;
     }
 
+    public boolean isAssigned() {
+        return (this.getClientId().length() > 0) && (this.getClientSecret().length() > 0);
+    }
+
     @Extension
     public static class DescriptorImpl extends BaseStandardCredentialsDescriptor {