diff --git a/languages/jetbrains.mps.jchr/generator/template/main@generator.mps b/languages/jetbrains.mps.jchr/generator/template/main@generator.mps
index 62dddd64..a797976b 100644
--- a/languages/jetbrains.mps.jchr/generator/template/main@generator.mps
+++ b/languages/jetbrains.mps.jchr/generator/template/main@generator.mps
@@ -21,8 +21,8 @@
     <import index="tp68" ref="r:00000000-0000-4000-0000-011c895903ac(jetbrains.mps.baseLanguageInternal.structure)" />
     <import index="mhbf" ref="8865b7a8-5271-43d3-884c-6fd1d9cfdd34/java:org.jetbrains.mps.openapi.model(MPS.OpenAPI/)" />
     <import index="w1kc" ref="6ed54515-acc8-4d1e-a16c-9fd6cfe951ea/java:jetbrains.mps.smodel(MPS.Core/)" />
-    <import index="tpck" ref="r:00000000-0000-4000-0000-011c89590288(jetbrains.mps.lang.core.structure)" implicit="true" />
     <import index="tpek" ref="r:00000000-0000-4000-0000-011c895902c0(jetbrains.mps.baseLanguage.behavior)" implicit="true" />
+    <import index="tpck" ref="r:00000000-0000-4000-0000-011c89590288(jetbrains.mps.lang.core.structure)" implicit="true" />
   </imports>
   <registry>
     <language id="13744753-c81f-424a-9c1b-cf8943bf4e86" name="jetbrains.mps.lang.sharedConcepts">
diff --git a/languages/jetbrains.mps.jchr/languageModels/behavior.mps b/languages/jetbrains.mps.jchr/languageModels/behavior.mps
index 8f26f44c..260089c4 100644
--- a/languages/jetbrains.mps.jchr/languageModels/behavior.mps
+++ b/languages/jetbrains.mps.jchr/languageModels/behavior.mps
@@ -1914,5 +1914,77 @@
       </node>
     </node>
   </node>
+  <node concept="13h7C7" id="2KSgAgVcjKo">
+    <property role="3GE5qa" value="handler.constraints" />
+    <ref role="13h7C2" to="vgt0:2KSgAgVcjDm" resolve="JavaExpressionConstraint" />
+    <node concept="13hLZK" id="2KSgAgVcjKp" role="13h7CW">
+      <node concept="3clFbS" id="2KSgAgVcjKq" role="2VODD2" />
+    </node>
+    <node concept="13i0hz" id="2KSgAgVcng0" role="13h7CS">
+      <property role="TrG5h" value="ident" />
+      <node concept="3Tm1VV" id="2KSgAgVcng1" role="1B3o_S" />
+      <node concept="3clFbS" id="2KSgAgVcng2" role="3clF47">
+        <node concept="3clFbF" id="2KSgAgVcoqs" role="3cqZAp">
+          <node concept="Xl_RD" id="2KSgAgVcoqD" role="3clFbG">
+            <property role="Xl_RC" value="expression" />
+          </node>
+        </node>
+      </node>
+      <node concept="17QB3L" id="2KSgAgVcoqm" role="3clF45" />
+    </node>
+    <node concept="13i0hz" id="2KSgAgVcjKr" role="13h7CS">
+      <property role="TrG5h" value="argument" />
+      <property role="13i0it" value="false" />
+      <property role="13i0iv" value="false" />
+      <ref role="13i0hy" node="5dz6b540JQV" resolve="argument" />
+      <node concept="3Tm1VV" id="2KSgAgVcjKs" role="1B3o_S" />
+      <node concept="3clFbS" id="2KSgAgVcjKv" role="3clF47">
+        <node concept="3clFbF" id="2KSgAgVcjNn" role="3cqZAp">
+          <node concept="2OqwBi" id="2KSgAgVcjNo" role="3clFbG">
+            <node concept="13iPFW" id="2KSgAgVcjNp" role="2Oq$k0" />
+            <node concept="3Tsc0h" id="2KSgAgVcjV3" role="2OqNvi">
+              <ref role="3TtcxE" to="vgt0:2KSgAgVcjDp" />
+            </node>
+          </node>
+        </node>
+      </node>
+      <node concept="2I9FWS" id="2KSgAgVcjKw" role="3clF45">
+        <ref role="2I9WkF" to="tpee:fz3vP1J" resolve="Expression" />
+      </node>
+    </node>
+    <node concept="13i0hz" id="2KSgAgVcjKx" role="13h7CS">
+      <property role="TrG5h" value="addArgument" />
+      <property role="13i0it" value="false" />
+      <property role="13i0iv" value="false" />
+      <ref role="13i0hy" node="5dz6b542vZH" resolve="addArgument" />
+      <node concept="3Tm1VV" id="2KSgAgVcjKy" role="1B3o_S" />
+      <node concept="3clFbS" id="2KSgAgVcjKB" role="3clF47">
+        <node concept="3clFbF" id="2KSgAgVcjZb" role="3cqZAp">
+          <node concept="2OqwBi" id="2KSgAgVcjZc" role="3clFbG">
+            <node concept="2OqwBi" id="2KSgAgVcjZd" role="2Oq$k0">
+              <node concept="13iPFW" id="2KSgAgVcjZe" role="2Oq$k0" />
+              <node concept="3Tsc0h" id="2KSgAgVckaa" role="2OqNvi">
+                <ref role="3TtcxE" to="vgt0:2KSgAgVcjDp" />
+              </node>
+            </node>
+            <node concept="TSZUe" id="2KSgAgVcjZg" role="2OqNvi">
+              <node concept="37vLTw" id="2KSgAgVcjZh" role="25WWJ7">
+                <ref role="3cqZAo" node="2KSgAgVcjKC" resolve="expression" />
+              </node>
+            </node>
+          </node>
+        </node>
+      </node>
+      <node concept="37vLTG" id="2KSgAgVcjKC" role="3clF46">
+        <property role="TrG5h" value="expression" />
+        <node concept="3Tqbb2" id="2KSgAgVcjKD" role="1tU5fm">
+          <ref role="ehGHo" to="tpee:fz3vP1J" resolve="Expression" />
+        </node>
+      </node>
+      <node concept="3Tqbb2" id="2KSgAgVcjKE" role="3clF45">
+        <ref role="ehGHo" to="tpee:fz3vP1J" resolve="Expression" />
+      </node>
+    </node>
+  </node>
 </model>
 
diff --git a/languages/jetbrains.mps.jchr/languageModels/editor.mps b/languages/jetbrains.mps.jchr/languageModels/editor.mps
index 53e83325..ae1f8c4b 100644
--- a/languages/jetbrains.mps.jchr/languageModels/editor.mps
+++ b/languages/jetbrains.mps.jchr/languageModels/editor.mps
@@ -1285,5 +1285,59 @@
       <node concept="l2Vlx" id="4EfgX2Esj$j" role="2iSdaV" />
     </node>
   </node>
+  <node concept="24kQdi" id="2KSgAgVcjD$">
+    <property role="3GE5qa" value="handler.constraints" />
+    <ref role="1XX52x" to="vgt0:2KSgAgVcjDm" resolve="JavaExpressionConstraint" />
+    <node concept="3EZMnI" id="2KSgAgVcjDA" role="2wV5jI">
+      <node concept="3F0ifn" id="2KSgAgVcjDH" role="3EZMnx">
+        <property role="3F0ifm" value="expression" />
+        <ref role="1k5W1q" to="tpen:6H7j4iMM5Cm" resolve="MPSMethodCall" />
+      </node>
+      <node concept="3F0ifn" id="2KSgAgVcjDR" role="3EZMnx">
+        <property role="3F0ifm" value="(" />
+        <ref role="1k5W1q" to="tpen:hY9fg1G" resolve="LeftParenAfterName" />
+      </node>
+      <node concept="3F0A7n" id="2KSgAgVcjDN" role="3EZMnx">
+        <ref role="1NtTu8" to="vgt0:2KSgAgVcjDt" resolve="symbolId" />
+      </node>
+      <node concept="3EZMnI" id="2KSgAgVfUe0" role="3EZMnx">
+        <node concept="VPM3Z" id="2KSgAgVfUe2" role="3F10Kt">
+          <property role="VOm3f" value="false" />
+        </node>
+        <node concept="l2Vlx" id="2KSgAgVfUe5" role="2iSdaV" />
+        <node concept="3F0ifn" id="2KSgAgVfIUb" role="3EZMnx">
+          <property role="3F0ifm" value="," />
+          <node concept="11L4FC" id="2KSgAgVfIVW" role="3F10Kt">
+            <property role="VOm3f" value="true" />
+          </node>
+        </node>
+        <node concept="3F2HdR" id="2KSgAgVcjDS" role="3EZMnx">
+          <property role="2czwfO" value="," />
+          <ref role="1NtTu8" to="vgt0:2KSgAgVcjDp" />
+          <node concept="l2Vlx" id="2KSgAgVcjDT" role="2czzBx" />
+        </node>
+        <node concept="pkWqt" id="2KSgAgVfUeG" role="pqm2j">
+          <node concept="3clFbS" id="2KSgAgVfUeH" role="2VODD2">
+            <node concept="3clFbF" id="2KSgAgVfUfZ" role="3cqZAp">
+              <node concept="2OqwBi" id="2KSgAgVfUWq" role="3clFbG">
+                <node concept="2OqwBi" id="2KSgAgVfUj2" role="2Oq$k0">
+                  <node concept="pncrf" id="2KSgAgVfUfY" role="2Oq$k0" />
+                  <node concept="3Tsc0h" id="2KSgAgVfUtW" role="2OqNvi">
+                    <ref role="3TtcxE" to="vgt0:2KSgAgVcjDp" />
+                  </node>
+                </node>
+                <node concept="3GX2aA" id="2KSgAgVfWx4" role="2OqNvi" />
+              </node>
+            </node>
+          </node>
+        </node>
+      </node>
+      <node concept="3F0ifn" id="2KSgAgVfITB" role="3EZMnx">
+        <property role="3F0ifm" value=")" />
+        <ref role="1k5W1q" to="tpen:hFCSUmN" resolve="RightParen" />
+      </node>
+      <node concept="l2Vlx" id="2KSgAgVcjDD" role="2iSdaV" />
+    </node>
+  </node>
 </model>
 
diff --git a/languages/jetbrains.mps.jchr/languageModels/structure.mps b/languages/jetbrains.mps.jchr/languageModels/structure.mps
index c3c6f8e9..3e28bc0d 100644
--- a/languages/jetbrains.mps.jchr/languageModels/structure.mps
+++ b/languages/jetbrains.mps.jchr/languageModels/structure.mps
@@ -447,5 +447,21 @@
       <ref role="AX2Wp" to="tpee:fKFJPy9" resolve="_Identifier_String" />
     </node>
   </node>
+  <node concept="1TIwiD" id="2KSgAgVcjDm">
+    <property role="1pbfSe" value="1734966458" />
+    <property role="3GE5qa" value="handler.constraints" />
+    <property role="TrG5h" value="JavaExpressionConstraint" />
+    <ref role="1TJDcQ" node="5dz6b540Jzm" resolve="AbstractConstraint" />
+    <node concept="1TJgyi" id="2KSgAgVcjDt" role="1TKVEl">
+      <property role="TrG5h" value="expressionId" />
+      <ref role="AX2Wp" to="tpck:fKAOsGN" resolve="string" />
+    </node>
+    <node concept="1TJgyj" id="2KSgAgVcjDp" role="1TKVEi">
+      <property role="20lmBu" value="aggregation" />
+      <property role="20kJfa" value="actualArgument" />
+      <property role="20lbJX" value="0..n" />
+      <ref role="20lvS9" to="tpee:fz3vP1J" resolve="Expression" />
+    </node>
+  </node>
 </model>
 
diff --git a/languages/jetbrains.mps.jchr/languageModels/textGen.mps b/languages/jetbrains.mps.jchr/languageModels/textGen.mps
index 6545b0ef..60274fe9 100644
--- a/languages/jetbrains.mps.jchr/languageModels/textGen.mps
+++ b/languages/jetbrains.mps.jchr/languageModels/textGen.mps
@@ -15,6 +15,7 @@
     <import index="1f2y" ref="r:c2e9552f-aeab-4773-af70-c663afdf96a5(jetbrains.mps.jchr.behavior)" />
     <import index="vgt0" ref="r:f36c95e5-e428-4945-91ae-1005e20c7971(jetbrains.mps.jchr.structure)" />
     <import index="tpck" ref="r:00000000-0000-4000-0000-011c89590288(jetbrains.mps.lang.core.structure)" implicit="true" />
+    <import index="wyt6" ref="6354ebe7-c22a-4a0f-ac54-50b52ab9b065/java:java.lang(JDK/)" implicit="true" />
   </imports>
   <registry>
     <language id="a247e09e-2435-45ba-b8d2-07e93feba96a" name="jetbrains.mps.baseLanguage.tuples">
@@ -157,6 +158,7 @@
     </language>
     <language id="83888646-71ce-4f1c-9c53-c54016f6ad4f" name="jetbrains.mps.baseLanguage.collections">
       <concept id="1151702311717" name="jetbrains.mps.baseLanguage.collections.structure.ToListOperation" flags="nn" index="ANE8D" />
+      <concept id="1162935959151" name="jetbrains.mps.baseLanguage.collections.structure.GetSizeOperation" flags="nn" index="34oBXx" />
       <concept id="1225711141656" name="jetbrains.mps.baseLanguage.collections.structure.ListElementAccessExpression" flags="nn" index="1y4W85">
         <child id="1225711182005" name="list" index="1y566C" />
         <child id="1225711191269" name="index" index="1y58nS" />
@@ -1189,5 +1191,96 @@
       </node>
     </node>
   </node>
+  <node concept="WtQ9Q" id="2KSgAgVcmAp">
+    <property role="3GE5qa" value="handler.constraints" />
+    <ref role="WuzLi" to="vgt0:2KSgAgVcjDm" resolve="JavaExpressionConstraint" />
+    <node concept="11bSqf" id="2KSgAgVcmAq" role="11c4hB">
+      <node concept="3clFbS" id="2KSgAgVcmAr" role="2VODD2">
+        <node concept="lc7rE" id="2KSgAgVcmQQ" role="3cqZAp">
+          <node concept="l9hG8" id="2KSgAgVcmQR" role="lcghm">
+            <node concept="2OqwBi" id="2KSgAgVcoPJ" role="lb14g">
+              <node concept="117lpO" id="2KSgAgVcoNi" role="2Oq$k0" />
+              <node concept="2qgKlT" id="2KSgAgVcp1e" role="2OqNvi">
+                <ref role="37wK5l" to="1f2y:2KSgAgVcng0" resolve="ident" />
+              </node>
+            </node>
+          </node>
+          <node concept="l9hG8" id="1ggxSI7mfTE" role="lcghm">
+            <node concept="2YIFZM" id="1ggxSI7mioL" role="lb14g">
+              <ref role="1Pybhc" to="wyt6:~String" resolve="String" />
+              <ref role="37wK5l" to="wyt6:~String.valueOf(int):java.lang.String" resolve="valueOf" />
+              <node concept="2OqwBi" id="1ggxSI7mgTD" role="37wK5m">
+                <node concept="2OqwBi" id="1ggxSI7mgd3" role="2Oq$k0">
+                  <node concept="117lpO" id="1ggxSI7mgaH" role="2Oq$k0" />
+                  <node concept="3Tsc0h" id="1ggxSI7mgmI" role="2OqNvi">
+                    <ref role="3TtcxE" to="vgt0:2KSgAgVcjDp" />
+                  </node>
+                </node>
+                <node concept="34oBXx" id="1ggxSI7mijT" role="2OqNvi" />
+              </node>
+            </node>
+          </node>
+        </node>
+        <node concept="lc7rE" id="2KSgAgVcmQY" role="3cqZAp">
+          <node concept="la8eA" id="2KSgAgVcmQZ" role="lcghm">
+            <property role="lacIc" value="(" />
+          </node>
+        </node>
+        <node concept="lc7rE" id="2KSgAgVcppR" role="3cqZAp">
+          <node concept="la8eA" id="1ggxSI7gNZu" role="lcghm">
+            <property role="lacIc" value="&quot;" />
+          </node>
+          <node concept="l9hG8" id="2KSgAgVcpsE" role="lcghm">
+            <node concept="2OqwBi" id="2KSgAgVcpxg" role="lb14g">
+              <node concept="117lpO" id="2KSgAgVcpuP" role="2Oq$k0" />
+              <node concept="3TrcHB" id="2KSgAgVcpMA" role="2OqNvi">
+                <ref role="3TsBF5" to="vgt0:2KSgAgVcjDt" resolve="symbolId" />
+              </node>
+            </node>
+          </node>
+          <node concept="la8eA" id="1ggxSI7gO2w" role="lcghm">
+            <property role="lacIc" value="&quot;" />
+          </node>
+        </node>
+        <node concept="3clFbH" id="2KSgAgVcpRG" role="3cqZAp" />
+        <node concept="3clFbJ" id="2KSgAgVcmQW" role="3cqZAp">
+          <node concept="3clFbS" id="2KSgAgVcmQX" role="3clFbx">
+            <node concept="lc7rE" id="1ggxSI7hHrO" role="3cqZAp">
+              <node concept="la8eA" id="1ggxSI7hHrP" role="lcghm">
+                <property role="lacIc" value="," />
+              </node>
+            </node>
+            <node concept="lc7rE" id="2KSgAgVcmR0" role="3cqZAp">
+              <node concept="l9S2W" id="2KSgAgVcmR1" role="lcghm">
+                <property role="XA4eZ" value="true" />
+                <property role="lbP0B" value="," />
+                <node concept="2OqwBi" id="2KSgAgVcmR2" role="lbANJ">
+                  <node concept="117lpO" id="2KSgAgVcmR3" role="2Oq$k0" />
+                  <node concept="3Tsc0h" id="2KSgAgVcpcT" role="2OqNvi">
+                    <ref role="3TtcxE" to="vgt0:2KSgAgVcjDp" />
+                  </node>
+                </node>
+              </node>
+            </node>
+          </node>
+          <node concept="2OqwBi" id="2KSgAgVcmR7" role="3clFbw">
+            <node concept="2OqwBi" id="2KSgAgVcmR8" role="2Oq$k0">
+              <node concept="117lpO" id="2KSgAgVcmR9" role="2Oq$k0" />
+              <node concept="3Tsc0h" id="2KSgAgVcp78" role="2OqNvi">
+                <ref role="3TtcxE" to="vgt0:2KSgAgVcjDp" />
+              </node>
+            </node>
+            <node concept="3GX2aA" id="2KSgAgVcmRb" role="2OqNvi" />
+          </node>
+        </node>
+        <node concept="3clFbH" id="2KSgAgVcpUO" role="3cqZAp" />
+        <node concept="lc7rE" id="2KSgAgVcmR5" role="3cqZAp">
+          <node concept="la8eA" id="2KSgAgVcmR6" role="lcghm">
+            <property role="lacIc" value=")" />
+          </node>
+        </node>
+      </node>
+    </node>
+  </node>
 </model>