Allowed activity types are a property of case type

modules/opencase_entities/config/schema/oc_case_type.schema.yml

@@ -8,5 +8,8 @@ opencase_entities.oc_case_type.*:
     label:
       type: label
       label: 'Label'
+    allowedActivityTypes:
+      type: sequence
+      label: 'Allowed Activity Types'
     uuid:
       type: string

modules/opencase_entities/src/Entity/OCCaseType.php

@@ -55,4 +55,10 @@ class OCCaseType extends ConfigEntityBundleBase implements OCCaseTypeInterface {
    */
   protected $label;
 
+  /**
+   * Activity types that can be attached to this type of case.
+   *
+   * @var array
+   */
+  protected $allowedActivityTypes;
 }