MQE-2126: Can't modify DataEntity data

Author: okolesnyk

dev/tests/functional/tests/MFTF/DevDocs/Data/DeprecatedMessageData.xml

@@ -11,4 +11,7 @@
     <entity name="DeprecatedMessageData" deprecated="Entity is deprecated. Please use 'MessageData'.">
         <data key="message">Introduction to the Magento Functional Testing Framework</data>
     </entity>
+    <entity name="MessageData">
+        <data key="justSomeField">Some data</data>
+    </entity>
 </entities>

dev/tests/functional/tests/MFTF/DevDocs/Data/ExtendMessageData.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+ /**
+  * Copyright © Magento, Inc. All rights reserved.
+  * See COPYING.txt for license details.
+  */
+-->
+
+<entities xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+          xsi:noNamespaceSchemaLocation="../../../../../../../src/Magento/FunctionalTestingFramework/DataGenerator/etc/dataProfileSchema.xsd">
+    <entity name="MessageData">
+        <array key="numbers">
+            <item>Something New</item>
+        </array>
+    </entity>
+</entities>

dev/tests/functional/tests/MFTF/DevDocs/Data/MessageData.xml

@@ -10,5 +10,11 @@
           xsi:noNamespaceSchemaLocation="urn:magento:mftf:DataGenerator/etc/dataProfileSchema.xsd">
     <entity name="MessageData">
         <data key="message">Introduction to the Magento Functional Testing Framework</data>
+        <array key="numbers">
+            <item name="zero">0</item>
+            <item name="one">1</item>
+            <item name="two">2</item>
+            <item name="three">3</item>
+        </array>
     </entity>
 </entities>

dev/tests/functional/tests/MFTF/DevDocs/Test/DevDocsTest.xml

@@ -46,5 +46,6 @@
             <argument name="test" value="{{HelperData.entityField}}" />
             <argument name="entityTest" value="HelperData" />
         </actionGroup>
+        <comment userInput="{{MessageData.numbers}}" stepKey="outputMergedArray" />
     </test>
 </tests>

etc/di.xml

@@ -157,6 +157,7 @@
             <argument name="idAttributes" xsi:type="array">
                 <item name="/entities/entity" xsi:type="string">name</item>
                 <item name="/entities/entity/(data|array)" xsi:type="string">key</item>
+                <item name="/entities/entity/array/item" xsi:type="string">name</item>
                 <item name="/entities/entity/requiredEntity" xsi:type="string">type</item>
             </argument>
             <argument name="mergeablePaths" xsi:type="array">

src/Magento/FunctionalTestingFramework/DataGenerator/etc/dataProfileSchema.xsd

@@ -118,17 +118,32 @@
 
     <xs:complexType name="arrayType">
         <xs:sequence>
-            <xs:element name="item" type="xs:string" maxOccurs="unbounded" minOccurs="0">
-            <xs:annotation>
-                <xs:documentation>
-                    Individual piece of data to be passed in as part of the parrent array type.
-                </xs:documentation>
-            </xs:annotation>
+            <xs:element name="item" type="itemType" maxOccurs="unbounded" minOccurs="0">
+                <xs:annotation>
+                    <xs:documentation>
+                        Individual piece of data to be passed in as part of the parrent array type.
+                    </xs:documentation>
+                </xs:annotation>
             </xs:element>
         </xs:sequence>
         <xs:attribute type="xs:string" name="key" use="required"/>
     </xs:complexType>
 
+
+    <xs:complexType name="itemType">
+        <xs:simpleContent>
+            <xs:extension base="xs:string">
+                <xs:attribute type="xs:string" name="name" use="optional">
+                    <xs:annotation>
+                        <xs:documentation>
+                            Key attribute of item pair.
+                        </xs:documentation>
+                    </xs:annotation>
+                </xs:attribute>
+            </xs:extension>
+        </xs:simpleContent>
+    </xs:complexType>
+
     <xs:complexType name="requiredEntityType">
         <xs:simpleContent>
             <xs:extension base="xs:string">