Allow the PolicyConfigurationFactory to be set in support of #151

This makes sure the platform or authorization implementation can obtain
the PolicyConfigurationFactory

Signed-off-by: Arjan Tijms <arjan.tijms@omnifish.ee>

api/src/main/java/jakarta/security/jacc/PolicyConfigurationFactory.java

@@ -105,6 +105,19 @@ public static PolicyConfigurationFactory getPolicyConfigurationFactory() throws
         return policyConfigurationFactory;
     }
 
+    /**
+     * Set the system-wide PolicyFactory implementation.
+     *
+     * <p>
+     * If an implementation was set previously, it will be replaced.
+     *
+     * @param policyConfigurationFactory The PolicyConfigurationFactory instance, which may be null.
+     *
+     */
+    public static synchronized void setPolicyConfigurationFactory(PolicyConfigurationFactory policyConfigurationFactory) {
+        PolicyConfigurationFactory.policyConfigurationFactory = policyConfigurationFactory;
+    }
+
     /**
      * This static method uses a system property to find and instantiate (via a public constructor) a provider specific
      * factory implementation class.