add getSplittedAttributes helper

packages/core/src/helpers/getSplittedAttributes.ts

@@ -0,0 +1,21 @@
+import { AnyObject, ExtensionAttribute } from '../types'
+
+export default function getSplittedAttributes(
+  extensionAttributes: ExtensionAttribute[],
+  typeName: string,
+  attributes: AnyObject,
+): AnyObject {
+  return Object.fromEntries(Object
+    .entries(attributes)
+    .filter(([name]) => {
+      const extensionAttribute = extensionAttributes.find(item => {
+        return item.type === typeName && item.name === name
+      })
+
+      if (!extensionAttribute) {
+        return false
+      }
+
+      return extensionAttribute.attribute.keepOnSplit
+    }))
+}