diff --git a/samples/mpscore/languages/jetbrains.mps.baseLanguage.collectionsExt/models/jetbrains.mps.baseLanguage.collectionsExt.types.mps b/samples/mpscore/languages/jetbrains.mps.baseLanguage.collectionsExt/models/jetbrains.mps.baseLanguage.collectionsExt.types.mps
index 29a63693..598d5e8d 100644
--- a/samples/mpscore/languages/jetbrains.mps.baseLanguage.collectionsExt/models/jetbrains.mps.baseLanguage.collectionsExt.types.mps
+++ b/samples/mpscore/languages/jetbrains.mps.baseLanguage.collectionsExt/models/jetbrains.mps.baseLanguage.collectionsExt.types.mps
@@ -188,6 +188,13 @@
       <concept id="1169194658468" name="jetbrains.mps.lang.core.structure.INamedConcept" flags="ng" index="TrEIO">
         <property id="1169194664001" name="name" index="TrG5h" />
       </concept>
+      <concept id="709746936026466394" name="jetbrains.mps.lang.core.structure.ChildAttribute" flags="ng" index="3VBwX9">
+        <property id="709746936026609031" name="linkId" index="3V$3ak" />
+        <property id="709746936026609029" name="role_DebugInfo" index="3V$3am" />
+      </concept>
+      <concept id="4452961908202556907" name="jetbrains.mps.lang.core.structure.BaseCommentAttribute" flags="ng" index="1X3_iC">
+        <child id="3078666699043039389" name="commentedNode" index="8Wnug" />
+      </concept>
     </language>
     <language id="c7fb639f-be78-4307-89b0-b5959c3fa8c8" name="jetbrains.mps.lang.text">
       <concept id="155656958578482948" name="jetbrains.mps.lang.text.structure.Word" flags="nn" index="3oM_SD">
@@ -13642,14 +13649,18 @@
                 <node concept="3I6sU6" id="3Z1xyIw3H5P" role="3Ip0Jz">
                   <node concept="3IrJb3" id="1BcUSjgdL0H" role="3I6sU7">
                     <node concept="3clFbS" id="1BcUSjgdL0I" role="3IrJb0">
-                      <node concept="3Aqczg" id="1BcUSjgdL0J" role="3cqZAp">
-                        <node concept="3jm4v3" id="3Z1xyIw3H5T" role="3Aqpz8">
-                          <ref role="3jm46O" to="yh6q:3Z1xyIvWi5s" resolve="getSeqElementType" />
-                          <node concept="a7P8L" id="3Z1xyIw3H5U" role="3jm6SO">
-                            <ref role="a7OzE" node="3Z1xyIw3H5K" resolve="Elem" />
-                          </node>
-                          <node concept="a7P8L" id="3Z1xyIw3H5V" role="3jm6SO">
-                            <ref role="a7OzE" node="3Z1xyIw3H5J" resolve="Operand" />
+                      <node concept="1X3_iC" id="7XekScVOfP0" role="lGtFl">
+                        <property role="3V$3am" value="statement" />
+                        <property role="3V$3ak" value="f3061a53-9226-4cc5-a443-f952ceaf5816/1068580123136/1068581517665" />
+                        <node concept="3Aqczg" id="1BcUSjgdL0J" role="8Wnug">
+                          <node concept="3jm4v3" id="3Z1xyIw3H5T" role="3Aqpz8">
+                            <ref role="3jm46O" to="yh6q:3Z1xyIvWi5s" resolve="getSeqElementType" />
+                            <node concept="a7P8L" id="3Z1xyIw3H5U" role="3jm6SO">
+                              <ref role="a7OzE" node="3Z1xyIw3H5K" resolve="Elem" />
+                            </node>
+                            <node concept="a7P8L" id="3Z1xyIw3H5V" role="3jm6SO">
+                              <ref role="a7OzE" node="3Z1xyIw3H5J" resolve="Operand" />
+                            </node>
                           </node>
                         </node>
                       </node>
@@ -13659,8 +13670,14 @@
                           <node concept="a7P8L" id="1BcUSjgdOU3" role="3AunhB">
                             <ref role="a7OzE" node="3Z1xyIw3H5L" resolve="Arg" />
                           </node>
-                          <node concept="a7P8L" id="1BcUSjgdOU4" role="3AunhB">
-                            <ref role="a7OzE" node="3Z1xyIw3H5K" resolve="Elem" />
+                          <node concept="ns1u0" id="7XekScVOfOr" role="3AunhB">
+                            <ref role="ns1xF" to="kqnc:JOGAOsVt2a" resolve="classifier" />
+                            <node concept="nsMwS" id="7XekScVOfOD" role="ns1xD">
+                              <ref role="nsMwP" to="kqnc:JOGAOsVt2c" resolve="classifier" />
+                              <node concept="h$QuP" id="7XekScVOfOH" role="iSaTp">
+                                <ref role="h$OrH" to="wyt6:~Object" resolve="Object" />
+                              </node>
+                            </node>
                           </node>
                           <node concept="ns1u0" id="6u6$XO96VqB" role="3AunhB">
                             <ref role="ns1xF" to="kqnc:6u6$XO93ntc" resolve="feedback" />
@@ -13788,14 +13805,18 @@
                 <node concept="3I6sU6" id="3Z1xyIw3O1b" role="3Ip0Jz">
                   <node concept="3IrJb3" id="1BcUSjgdKPr" role="3I6sU7">
                     <node concept="3clFbS" id="1BcUSjgdKPs" role="3IrJb0">
-                      <node concept="3Aqczg" id="1BcUSjgdKPt" role="3cqZAp">
-                        <node concept="3jm4v3" id="3Z1xyIw3O1d" role="3Aqpz8">
-                          <ref role="3jm46O" to="yh6q:3Z1xyIvWi5s" resolve="getSeqElementType" />
-                          <node concept="a7P8L" id="3Z1xyIw3O1e" role="3jm6SO">
-                            <ref role="a7OzE" node="3Z1xyIw3O16" resolve="Elem" />
-                          </node>
-                          <node concept="a7P8L" id="3Z1xyIw3O1f" role="3jm6SO">
-                            <ref role="a7OzE" node="3Z1xyIw3O15" resolve="Operand" />
+                      <node concept="1X3_iC" id="7XekScVOfPs" role="lGtFl">
+                        <property role="3V$3am" value="statement" />
+                        <property role="3V$3ak" value="f3061a53-9226-4cc5-a443-f952ceaf5816/1068580123136/1068581517665" />
+                        <node concept="3Aqczg" id="1BcUSjgdKPt" role="8Wnug">
+                          <node concept="3jm4v3" id="3Z1xyIw3O1d" role="3Aqpz8">
+                            <ref role="3jm46O" to="yh6q:3Z1xyIvWi5s" resolve="getSeqElementType" />
+                            <node concept="a7P8L" id="3Z1xyIw3O1e" role="3jm6SO">
+                              <ref role="a7OzE" node="3Z1xyIw3O16" resolve="Elem" />
+                            </node>
+                            <node concept="a7P8L" id="3Z1xyIw3O1f" role="3jm6SO">
+                              <ref role="a7OzE" node="3Z1xyIw3O15" resolve="Operand" />
+                            </node>
                           </node>
                         </node>
                       </node>
@@ -13805,8 +13826,14 @@
                           <node concept="a7P8L" id="1BcUSjgdP01" role="3AunhB">
                             <ref role="a7OzE" node="3Z1xyIw3O17" resolve="Arg" />
                           </node>
-                          <node concept="a7P8L" id="1BcUSjgdP02" role="3AunhB">
-                            <ref role="a7OzE" node="3Z1xyIw3O16" resolve="Elem" />
+                          <node concept="ns1u0" id="7XekScVOfOK" role="3AunhB">
+                            <ref role="ns1xF" to="kqnc:JOGAOsVt2a" resolve="classifier" />
+                            <node concept="nsMwS" id="7XekScVOfOL" role="ns1xD">
+                              <ref role="nsMwP" to="kqnc:JOGAOsVt2c" resolve="classifier" />
+                              <node concept="h$QuP" id="7XekScVOfOM" role="iSaTp">
+                                <ref role="h$OrH" to="wyt6:~Object" resolve="Object" />
+                              </node>
+                            </node>
                           </node>
                           <node concept="ns1u0" id="6u6$XO96VqF" role="3AunhB">
                             <ref role="ns1xF" to="kqnc:6u6$XO93ntc" resolve="feedback" />
diff --git a/samples/mpscore/solutions/jetbrains.mps.baseLanguage.collectionsExt.test/models/jetbrains.mps.baseLanguage.collectionsExt.test.collections.mps b/samples/mpscore/solutions/jetbrains.mps.baseLanguage.collectionsExt.test/models/jetbrains.mps.baseLanguage.collectionsExt.test.collections.mps
index a3ce6b8b..dcfe132e 100644
--- a/samples/mpscore/solutions/jetbrains.mps.baseLanguage.collectionsExt.test/models/jetbrains.mps.baseLanguage.collectionsExt.test.collections.mps
+++ b/samples/mpscore/solutions/jetbrains.mps.baseLanguage.collectionsExt.test/models/jetbrains.mps.baseLanguage.collectionsExt.test.collections.mps
@@ -6250,9 +6250,6 @@
               <node concept="2WmjW8" id="3Z1xyIw4BgR" role="2OqNvi">
                 <node concept="37vLTw" id="3Z1xyIw4GwE" role="25WWJ7">
                   <ref role="3cqZAo" node="3Z1xyIvXE9D" resolve="a" />
-                  <node concept="1U20sH" id="3Z1xyIw4IXw" role="lGtFl">
-                    <property role="1U20sK" value="error" />
-                  </node>
                 </node>
               </node>
             </node>
@@ -6285,9 +6282,6 @@
               <node concept="32_xCg" id="3Z1xyIw4P2f" role="2OqNvi">
                 <node concept="37vLTw" id="3Z1xyIw4P2h" role="25WWJ7">
                   <ref role="3cqZAo" node="3Z1xyIvXE9D" resolve="a" />
-                  <node concept="1U20sH" id="3Z1xyIw4P2i" role="lGtFl">
-                    <property role="1U20sK" value="error" />
-                  </node>
                 </node>
               </node>
             </node>