public btGeneric6DofSpringConstraint createGeneric6DofSpringConstraint(
     btRigidBody rbA,
     btRigidBody rbB,
     Matrix4 frameInA,
     Matrix4 frameInB,
     boolean useLinearReferenceFrameA) {
   long cPtr =
       ExtrasJNI.btWorldImporter_createGeneric6DofSpringConstraint(
           swigCPtr,
           this,
           btRigidBody.getCPtr(rbA),
           rbA,
           btRigidBody.getCPtr(rbB),
           rbB,
           frameInA,
           frameInB,
           useLinearReferenceFrameA);
   return (cPtr == 0) ? null : new btGeneric6DofSpringConstraint(cPtr, false);
 }