diff --git a/utbot-framework-api/src/main/kotlin/org/utbot/framework/plugin/api/Api.kt b/utbot-framework-api/src/main/kotlin/org/utbot/framework/plugin/api/Api.kt
index 5ceb4aa28e..a225a50490 100644
--- a/utbot-framework-api/src/main/kotlin/org/utbot/framework/plugin/api/Api.kt
+++ b/utbot-framework-api/src/main/kotlin/org/utbot/framework/plugin/api/Api.kt
@@ -339,7 +339,7 @@ object UtVoidModel : UtModel(voidClassId)
  * Model for enum constant
  */
 data class UtEnumConstantModel(
-    override val id: Int?,
+    override val id: Int,
     override val classId: ClassId,
     val value: Enum<*>
 ) : UtReferenceModel(id, classId) {
@@ -351,7 +351,7 @@ data class UtEnumConstantModel(
  * Model for class reference
  */
 data class UtClassRefModel(
-    override val id: Int?,
+    override val id: Int,
     override val classId: ClassId,
     val value: Class<*>
 ) : UtReferenceModel(id, classId) {
@@ -455,9 +455,7 @@ data class UtArrayModel(
         return true
     }
 
-    override fun hashCode(): Int {
-        return id
-    }
+    override fun hashCode(): Int = id
 }
 
 /**
@@ -469,7 +467,7 @@ data class UtArrayModel(
  * @param modificationsChain is a chain of [UtStatementModel] to construct object state.
  */
 data class UtAssembleModel private constructor(
-    override val id: Int?,
+    override val id: Int,
     override val classId: ClassId,
     override val modelName: String,
     val instantiationCall: UtExecutableCallModel,
@@ -494,7 +492,7 @@ data class UtAssembleModel private constructor(
      * as [UtExecutableCallModel.instance].
      */
     constructor(
-        id: Int?,
+        id: Int,
         classId: ClassId,
         modelName: String,
         instantiationCall: UtExecutableCallModel,
@@ -524,9 +522,7 @@ data class UtAssembleModel private constructor(
         return id == other.id
     }
 
-    override fun hashCode(): Int {
-        return id ?: 0
-    }
+    override fun hashCode(): Int = id
 }
 
 /**
@@ -554,7 +550,7 @@ data class UtAssembleModel private constructor(
  */
 // TODO: what about support for Kotlin lambdas and function types? See https://github.com/UnitTestBot/UTBotJava/issues/852
 class UtLambdaModel(
-    override val id: Int?,
+    override val id: Int,
     val samType: ClassId,
     val declaringClass: ClassId,
     val lambdaName: String,
@@ -581,9 +577,7 @@ class UtLambdaModel(
         return true
     }
 
-    override fun hashCode(): Int {
-        return id ?: 0
-    }
+    override fun hashCode(): Int = id
 }
 
 /**
diff --git a/utbot-framework-api/src/main/kotlin/org/utbot/framework/process/OpenModulesContainer.kt b/utbot-framework-api/src/main/kotlin/org/utbot/framework/process/OpenModulesContainer.kt
index fb53e2fd10..650e7d40c4 100644
--- a/utbot-framework-api/src/main/kotlin/org/utbot/framework/process/OpenModulesContainer.kt
+++ b/utbot-framework-api/src/main/kotlin/org/utbot/framework/process/OpenModulesContainer.kt
@@ -15,6 +15,33 @@ object OpenModulesContainer {
             openPackage("java.base", "java.lang")
             openPackage("java.base", "java.lang.reflect")
             openPackage("java.base", "sun.security.provider")
+            openPackage("java.base", "jdk.internal.event")
+            openPackage("java.base", "jdk.internal.jimage")
+            openPackage("java.base", "jdk.internal.jimage.decompressor")
+            openPackage("java.base", "jdk.internal.jmod")
+            openPackage("java.base", "jdk.internal.jtrfs")
+            openPackage("java.base", "jdk.internal.loader")
+            openPackage("java.base", "jdk.internal.logger")
+            openPackage("java.base", "jdk.internal.math")
+            openPackage("java.base", "jdk.internal.misc")
+            openPackage("java.base", "jdk.internal.module")
+            openPackage("java.base", "jdk.internal.org.objectweb.asm.commons")
+            openPackage("java.base", "jdk.internal.org.objectweb.asm.signature")
+            openPackage("java.base", "jdk.internal.org.objectweb.asm.tree")
+            openPackage("java.base", "jdk.internal.org.objectweb.asm.tree.analysis")
+            openPackage("java.base", "jdk.internal.org.objectweb.asm.util")
+            openPackage("java.base", "jdk.internal.org.xml.sax")
+            openPackage("java.base", "jdk.internal.org.xml.sax.helpers")
+            openPackage("java.base", "jdk.internal.perf")
+            openPackage("java.base", "jdk.internal.platform")
+            openPackage("java.base", "jdk.internal.ref")
+            openPackage("java.base", "jdk.internal.reflect")
+            openPackage("java.base", "jdk.internal.util")
+            openPackage("java.base", "jdk.internal.util.jar")
+            openPackage("java.base", "jdk.internal.util.xml")
+            openPackage("java.base", "jdk.internal.util.xml.impl")
+            openPackage("java.base", "jdk.internal.vm")
+            openPackage("java.base", "jdk.internal.vm.annotation")
             add("--illegal-access=warn")
         }
     }