Extract an interface from QBitComponentMetaDataProducer (which itself is still useful as a base class, so you don't have to implement get/setQBitConfig yourself), for implementations that already have a different base class.

qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/model/metadata/qbits/QBitComponentMetaDataProducer.java

@@ -22,7 +22,6 @@
 package com.kingsrook.qqq.backend.core.model.metadata.qbits;
 
 
-import com.kingsrook.qqq.backend.core.model.metadata.MetaDataProducerInterface;
 import com.kingsrook.qqq.backend.core.model.metadata.MetaDataProducerOutput;
 
 
@@ -33,7 +32,7 @@ import com.kingsrook.qqq.backend.core.model.metadata.MetaDataProducerOutput;
  ** Specifically exists to accept the QBitConfig as a type parameter and a value,
  ** easily accessed in the producer's methods as getQBitConfig()
  *******************************************************************************/
-public abstract class QBitComponentMetaDataProducer<T extends MetaDataProducerOutput, C extends QBitConfig> implements MetaDataProducerInterface<T>
+public abstract class QBitComponentMetaDataProducer<T extends MetaDataProducerOutput, C extends QBitConfig> implements QBitComponentMetaDataProducerInterface<T, C>
 {
    private C qBitConfig = null;
 
@@ -42,6 +41,7 @@ public abstract class QBitComponentMetaDataProducer<T extends MetaDataProducerOu
    /*******************************************************************************
     ** Getter for qBitConfig
     *******************************************************************************/
+   @Override
    public C getQBitConfig()
    {
       return (this.qBitConfig);
@@ -52,6 +52,7 @@ public abstract class QBitComponentMetaDataProducer<T extends MetaDataProducerOu
    /*******************************************************************************
     ** Setter for qBitConfig
     *******************************************************************************/
+   @Override
    public void setQBitConfig(C qBitConfig)
    {
       this.qBitConfig = qBitConfig;

qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/model/metadata/qbits/QBitComponentMetaDataProducerInterface.java

@@ -0,0 +1,50 @@
+/*
+ * QQQ - Low-code Application Framework for Engineers.
+ * Copyright (C) 2021-2025.  Kingsrook, LLC
+ * 651 N Broad St Ste 205 # 6917 | Middletown DE 19709 | United States
+ * contact@kingsrook.com
+ * https://github.com/Kingsrook/
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.kingsrook.qqq.backend.core.model.metadata.qbits;
+
+
+import com.kingsrook.qqq.backend.core.model.metadata.MetaDataProducerInterface;
+import com.kingsrook.qqq.backend.core.model.metadata.MetaDataProducerOutput;
+
+
+/*******************************************************************************
+ ** extension of MetaDataProducerInterface, designed for producing meta data
+ ** within a (java-defined, at this time) QBit.
+ **
+ ** Specifically exists to accept the QBitConfig as a type parameter and a value,
+ ** easily accessed in the producer's methods as getQBitConfig()
+ *******************************************************************************/
+public interface QBitComponentMetaDataProducerInterface<T extends MetaDataProducerOutput, C extends QBitConfig> extends MetaDataProducerInterface<T>
+{
+
+   /*******************************************************************************
+    ** Getter for qBitConfig
+    *******************************************************************************/
+   C getQBitConfig();
+
+
+   /*******************************************************************************
+    ** Setter for qBitConfig
+    *******************************************************************************/
+   void setQBitConfig(C qBitConfig);
+
+}

qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/model/metadata/qbits/QBitProducer.java

@@ -81,9 +81,9 @@ public interface QBitProducer
       ///////////////////////////////
       for(MetaDataProducerInterface<?> producer : producers)
       {
-         if(producer instanceof QBitComponentMetaDataProducer<?, ?>)
+         if(producer instanceof QBitComponentMetaDataProducerInterface<?,?>)
          {
-            QBitComponentMetaDataProducer<?, C> qBitComponentMetaDataProducer = (QBitComponentMetaDataProducer<?, C>) producer;
+            QBitComponentMetaDataProducerInterface<?,C> qBitComponentMetaDataProducer = (QBitComponentMetaDataProducerInterface<?,C>) producer;
             qBitComponentMetaDataProducer.setQBitConfig(qBitConfig);
          }