refactor: extract getFirstTypeArgumentFromInterface method

Author: metacosm

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/config/ResourceConfiguration.java

@@ -27,9 +27,9 @@ default String getLabelSelector() {
     return null;
   }
 
+  @SuppressWarnings("unchecked")
   default Class<R> getResourceClass() {
-    ParameterizedType type = (ParameterizedType) getClass().getGenericInterfaces()[0];
-    return (Class<R>) type.getActualTypeArguments()[0];
+    return (Class<R>) Utils.getFirstTypeArgumentFromInterface(getClass());
   }
 
   default Set<String> getNamespaces() {

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/config/Utils.java

@@ -1,6 +1,7 @@
 package io.javaoperatorsdk.operator.api.config;
 
 import java.io.IOException;
+import java.lang.reflect.ParameterizedType;
 import java.text.SimpleDateFormat;
 import java.time.Instant;
 import java.util.Date;
@@ -67,4 +68,9 @@ public static boolean shouldCheckCRDAndValidateLocalModel() {
   public static boolean debugThreadPool() {
     return Boolean.getBoolean(System.getProperty(DEBUG_THREAD_POOL_ENV_KEY, "false"));
   }
+
+  public static Class<?> getFirstTypeArgumentFromInterface(Class<?> clazz) {
+    ParameterizedType type = (ParameterizedType) clazz.getGenericInterfaces()[0];
+    return (Class<?>) type.getActualTypeArguments()[0];
+  }
 }