diff --git a/context-tests/src/test/kotlin/io/spine/tools/validation/AssumedRequiredIdSpec.kt b/context-tests/src/test/kotlin/io/spine/tools/validation/AssumedRequiredIdSpec.kt
new file mode 100644
index 0000000000..478865aa3b
--- /dev/null
+++ b/context-tests/src/test/kotlin/io/spine/tools/validation/AssumedRequiredIdSpec.kt
@@ -0,0 +1,94 @@
+/*
+ * Copyright 2026, TeamDev. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package io.spine.tools.validation
+
+import com.google.protobuf.Descriptors.Descriptor
+import io.kotest.matchers.string.shouldNotContain
+import io.spine.logging.testing.ConsoleTap
+import io.spine.logging.testing.tapConsole
+import io.spine.testing.compiler.PipelineSetup
+import io.spine.testing.compiler.acceptingOnly
+import io.spine.testing.compiler.pipelineParams
+import io.spine.testing.compiler.withRequestFile
+import io.spine.testing.compiler.withSettingsDir
+import io.spine.tools.code.SourceSetName
+import io.spine.tools.compiler.params.WorkingDirectory
+import io.spine.tools.compiler.protobuf.field
+import io.spine.tools.validation.given.EntityWithInt32Id
+import java.nio.file.Path
+import kotlin.io.path.createDirectories
+import org.junit.jupiter.api.BeforeAll
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.io.TempDir
+
+@DisplayName("Assumed `(required)` entity IDs should")
+internal class AssumedRequiredIdSpec {
+
+    @TempDir
+    lateinit var workingDir: Path
+
+    @Test
+    fun `not emit a warning for an int32 field`() {
+        val descriptor = EntityWithInt32Id.getDescriptor()
+        val output = compile(descriptor)
+        val field = descriptor.field("id")
+
+        output shouldNotContain field.fullName
+        output shouldNotContain "should not be declared as `(required)`"
+        output shouldNotContain "assumed to be required"
+    }
+
+    private fun compile(descriptor: Descriptor): String {
+        val wd = WorkingDirectory(workingDir)
+        val outputDir = workingDir.resolve("output")
+        outputDir.createDirectories()
+        val params = pipelineParams {
+            withRequestFile(wd.requestDirectory.file(SourceSetName("testFixtures")))
+            withSettingsDir(wd.settingsDirectory.path)
+        }
+        val setup = PipelineSetup.byResources(
+            params,
+            plugins = listOf(object : ValidationPlugin() {}),
+            outputRoot = outputDir,
+            descriptorFilter = acceptingOnly(descriptor)
+        ) {}
+        val pipeline = setup.createPipeline()
+        return tapConsole {
+            pipeline()
+        }
+    }
+
+    companion object {
+
+        @JvmStatic
+        @BeforeAll
+        fun installConsoleTap() {
+            ConsoleTap.install()
+        }
+    }
+}
diff --git a/context-tests/src/testFixtures/proto/spine/validation/assumed_required_id_spec.proto b/context-tests/src/testFixtures/proto/spine/validation/assumed_required_id_spec.proto
new file mode 100644
index 0000000000..c574431880
--- /dev/null
+++ b/context-tests/src/testFixtures/proto/spine/validation/assumed_required_id_spec.proto
@@ -0,0 +1,42 @@
+/*
+ * Copyright 2026, TeamDev. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+syntax = "proto3";
+
+package spine.validation.stubs;
+
+import "spine/options.proto";
+
+option (type_url_prefix) = "type.spine.io";
+option java_package = "io.spine.tools.validation.given";
+option java_outer_classname = "AssumedRequiredIdSpecProto";
+option java_multiple_files = true;
+
+message EntityWithInt32Id {
+    option (entity).kind = ENTITY;
+
+    int32 id = 1;
+}
diff --git a/docs/content/docs/validation/developer/build-and-release.md b/docs/content/docs/validation/developer/build-and-release.md
index 6ef2ecc511..dc0ca90609 100644
--- a/docs/content/docs/validation/developer/build-and-release.md
+++ b/docs/content/docs/validation/developer/build-and-release.md
@@ -47,7 +47,7 @@ through Gradle's `extra` properties:
   end="val validationVersion">
 </embed-code>
 ```kotlin
-val validationVersion by extra("2.0.0-SNAPSHOT.420")
+val validationVersion by extra("2.0.0-SNAPSHOT.421")
 ```
 
 The root build script applies this file under `allprojects { … }` and assigns
diff --git a/docs/content/docs/validation/user/01-getting-started/adding-to-build.md b/docs/content/docs/validation/user/01-getting-started/adding-to-build.md
index d5bf9d49fc..ab88f3805d 100644
--- a/docs/content/docs/validation/user/01-getting-started/adding-to-build.md
+++ b/docs/content/docs/validation/user/01-getting-started/adding-to-build.md
@@ -90,7 +90,7 @@ Add the Validation plugin to the build.
 ```kotlin
 plugins {
     module
-    id("io.spine.validation") version "2.0.0-SNAPSHOT.420"
+    id("io.spine.validation") version "2.0.0-SNAPSHOT.421"
 }
 ```
 
diff --git a/docs/dependencies/dependencies.md b/docs/dependencies/dependencies.md
index 041de692fe..ff071b1499 100644
--- a/docs/dependencies/dependencies.md
+++ b/docs/dependencies/dependencies.md
@@ -1,6 +1,6 @@
 
 
-# Dependencies of `io.spine.tools:validation-context:2.0.0-SNAPSHOT.420`
+# Dependencies of `io.spine.tools:validation-context:2.0.0-SNAPSHOT.421`
 
 ## Runtime
 1.  **Group** : com.fasterxml.jackson. **Name** : jackson-bom. **Version** : 2.20.0.
@@ -1097,7 +1097,7 @@ This report was generated on **Wed May 13 20:44:36 WEST 2026** using
 
 
 
-# Dependencies of `io.spine.tools:validation-context-tests:2.0.0-SNAPSHOT.420`
+# Dependencies of `io.spine.tools:validation-context-tests:2.0.0-SNAPSHOT.421`
 
 ## Runtime
 1.  **Group** : com.fasterxml.jackson. **Name** : jackson-bom. **Version** : 2.20.0.
@@ -1798,7 +1798,7 @@ This report was generated on **Wed May 13 20:44:36 WEST 2026** using
 
 
 
-# Dependencies of `io.spine.tools:validation-docs:2.0.0-SNAPSHOT.420`
+# Dependencies of `io.spine.tools:validation-docs:2.0.0-SNAPSHOT.421`
 
 ## Runtime
 ## Compile, tests, and tooling
@@ -1812,7 +1812,7 @@ This report was generated on **Wed May 13 20:09:04 WEST 2026** using
 
 
 
-# Dependencies of `io.spine.tools:validation-gradle-plugin:2.0.0-SNAPSHOT.420`
+# Dependencies of `io.spine.tools:validation-gradle-plugin:2.0.0-SNAPSHOT.421`
 
 ## Runtime
 1.  **Group** : com.fasterxml.jackson. **Name** : jackson-bom. **Version** : 2.20.0.
@@ -2871,7 +2871,7 @@ This report was generated on **Wed May 13 20:44:36 WEST 2026** using
 
 
 
-# Dependencies of `io.spine.tools:validation-java:2.0.0-SNAPSHOT.420`
+# Dependencies of `io.spine.tools:validation-java:2.0.0-SNAPSHOT.421`
 
 ## Runtime
 1.  **Group** : com.fasterxml.jackson. **Name** : jackson-bom. **Version** : 2.20.0.
@@ -3968,7 +3968,7 @@ This report was generated on **Wed May 13 20:44:36 WEST 2026** using
 
 
 
-# Dependencies of `io.spine.tools:validation-java-bundle:2.0.0-SNAPSHOT.420`
+# Dependencies of `io.spine.tools:validation-java-bundle:2.0.0-SNAPSHOT.421`
 
 ## Runtime
 1.  **Group** : org.jetbrains. **Name** : annotations. **Version** : 13.0.
@@ -4022,7 +4022,7 @@ This report was generated on **Wed May 13 20:44:35 WEST 2026** using
 
 
 
-# Dependencies of `io.spine:spine-validation-jvm-runtime:2.0.0-SNAPSHOT.420`
+# Dependencies of `io.spine:spine-validation-jvm-runtime:2.0.0-SNAPSHOT.421`
 
 ## Runtime
 1.  **Group** : com.google.code.findbugs. **Name** : jsr305. **Version** : 3.0.2.
@@ -4829,7 +4829,7 @@ This report was generated on **Wed May 13 20:44:36 WEST 2026** using
 
 
 
-# Dependencies of `io.spine.tools:validation-consumer:2.0.0-SNAPSHOT.420`
+# Dependencies of `io.spine.tools:validation-consumer:2.0.0-SNAPSHOT.421`
 
 ## Runtime
 1.  **Group** : com.fasterxml.jackson. **Name** : jackson-bom. **Version** : 2.20.0.
@@ -5518,7 +5518,7 @@ This report was generated on **Wed May 13 20:44:36 WEST 2026** using
 
 
 
-# Dependencies of `io.spine.tools:validation-consumer-dependency:2.0.0-SNAPSHOT.420`
+# Dependencies of `io.spine.tools:validation-consumer-dependency:2.0.0-SNAPSHOT.421`
 
 ## Runtime
 1.  **Group** : com.google.code.findbugs. **Name** : jsr305. **Version** : 3.0.2.
@@ -5983,7 +5983,7 @@ This report was generated on **Wed May 13 20:44:36 WEST 2026** using
 
 
 
-# Dependencies of `io.spine.tools:validation-extensions:2.0.0-SNAPSHOT.420`
+# Dependencies of `io.spine.tools:validation-extensions:2.0.0-SNAPSHOT.421`
 
 ## Runtime
 1.  **Group** : com.fasterxml.jackson. **Name** : jackson-bom. **Version** : 2.20.0.
@@ -6609,7 +6609,7 @@ This report was generated on **Wed May 13 20:44:36 WEST 2026** using
 
 
 
-# Dependencies of `io.spine.tools:validation-runtime:2.0.0-SNAPSHOT.420`
+# Dependencies of `io.spine.tools:validation-runtime:2.0.0-SNAPSHOT.421`
 
 ## Runtime
 1.  **Group** : com.google.code.findbugs. **Name** : jsr305. **Version** : 3.0.2.
@@ -7177,7 +7177,7 @@ This report was generated on **Wed May 13 20:44:36 WEST 2026** using
 
 
 
-# Dependencies of `io.spine.tools:validation-validating:2.0.0-SNAPSHOT.420`
+# Dependencies of `io.spine.tools:validation-validating:2.0.0-SNAPSHOT.421`
 
 ## Runtime
 1.  **Group** : com.google.code.findbugs. **Name** : jsr305. **Version** : 3.0.2.
@@ -7788,7 +7788,7 @@ This report was generated on **Wed May 13 20:44:36 WEST 2026** using
 
 
 
-# Dependencies of `io.spine.tools:validation-validator:2.0.0-SNAPSHOT.420`
+# Dependencies of `io.spine.tools:validation-validator:2.0.0-SNAPSHOT.421`
 
 ## Runtime
 1.  **Group** : com.fasterxml.jackson. **Name** : jackson-bom. **Version** : 2.20.0.
@@ -8533,7 +8533,7 @@ This report was generated on **Wed May 13 20:44:36 WEST 2026** using
 
 
 
-# Dependencies of `io.spine.tools:validation-validator-dependency:2.0.0-SNAPSHOT.420`
+# Dependencies of `io.spine.tools:validation-validator-dependency:2.0.0-SNAPSHOT.421`
 
 ## Runtime
 1.  **Group** : com.google.code.findbugs. **Name** : jsr305. **Version** : 3.0.2.
@@ -8773,7 +8773,7 @@ This report was generated on **Wed May 13 20:44:35 WEST 2026** using
 
 
 
-# Dependencies of `io.spine.tools:validation-vanilla:2.0.0-SNAPSHOT.420`
+# Dependencies of `io.spine.tools:validation-vanilla:2.0.0-SNAPSHOT.421`
 
 ## Runtime
 1.  **Group** : com.google.code.findbugs. **Name** : jsr305. **Version** : 3.0.2.
diff --git a/docs/dependencies/pom.xml b/docs/dependencies/pom.xml
index c57129ad5c..133b9969ac 100644
--- a/docs/dependencies/pom.xml
+++ b/docs/dependencies/pom.xml
@@ -10,7 +10,7 @@ all modules and does not describe the project structure per-subproject.
  -->
 <groupId>io.spine.tools</groupId>
 <artifactId>validation</artifactId>
-<version>2.0.0-SNAPSHOT.420</version>
+<version>2.0.0-SNAPSHOT.421</version>
 
 <inceptionYear>2015</inceptionYear>
 
diff --git a/java/src/main/kotlin/io/spine/tools/validation/java/generate/option/RequiredGenerator.kt b/java/src/main/kotlin/io/spine/tools/validation/java/generate/option/RequiredGenerator.kt
index 6e80f8a85f..91700e70c3 100644
--- a/java/src/main/kotlin/io/spine/tools/validation/java/generate/option/RequiredGenerator.kt
+++ b/java/src/main/kotlin/io/spine/tools/validation/java/generate/option/RequiredGenerator.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright 2025, TeamDev. All rights reserved.
+ * Copyright 2026, TeamDev. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -48,8 +48,9 @@ import io.spine.tools.validation.java.generate.SingleOptionCode
 import io.spine.tools.validation.java.generate.ValidateScope.parentName
 import io.spine.tools.validation.java.generate.ValidateScope.parentPath
 import io.spine.tools.validation.java.generate.ValidateScope.violations
-import io.spine.tools.validation.option.IF_MISSING
+import io.spine.tools.validation.option.required.RequiredFieldSupport.isSupported
 import io.spine.validation.ConstraintViolation
+import io.spine.tools.validation.option.IF_MISSING
 import io.spine.validation.ErrorPlaceholder
 import io.spine.validation.ErrorPlaceholder.FIELD_PATH
 import io.spine.validation.ErrorPlaceholder.FIELD_TYPE
@@ -71,6 +72,7 @@ internal class RequiredGenerator : OptionGeneratorWithConverter() {
     override fun codeFor(type: TypeName): List<SingleOptionCode> =
         allRequiredFields
             .filter { it.id.type == type }
+            .filter { it.subject.type.isSupported() }
             .map { GenerateRequired(it, converter).code() }
 }
 
diff --git a/java/src/main/kotlin/io/spine/tools/validation/java/generate/option/bound/BoundedFieldGenerator.kt b/java/src/main/kotlin/io/spine/tools/validation/java/generate/option/bound/BoundedFieldGenerator.kt
index e630732e1c..d6f2caa6d7 100644
--- a/java/src/main/kotlin/io/spine/tools/validation/java/generate/option/bound/BoundedFieldGenerator.kt
+++ b/java/src/main/kotlin/io/spine/tools/validation/java/generate/option/bound/BoundedFieldGenerator.kt
@@ -26,6 +26,7 @@
 
 package io.spine.tools.validation.java.generate.option.bound
 
+import io.spine.annotation.VisibleForTesting
 import io.spine.base.FieldPath
 import io.spine.string.camelCase
 import io.spine.tools.compiler.Compilation
@@ -69,6 +70,7 @@ import io.spine.tools.validation.java.generate.option.bound.Docs.UNSIGNED_API
 import io.spine.type.TypeName
 import io.spine.validation.ConstraintViolation
 import io.spine.validation.ErrorPlaceholder
+import java.util.concurrent.ConcurrentHashMap
 
 /**
  * An abstract base for field generators that restrict the range of numeric fields.
@@ -120,11 +122,9 @@ internal abstract class BoundedFieldGenerator(
      * of [ConstraintViolation] and adds it to the [violations] list.
      */
     private fun checkWithinBounds(value: Expression<Number>): CodeBlock {
-        // TODO:2025-05-12:yevhenii.nadtochii: Enable reporting back when we decide upon the format.
-        //  Issue: https://github.com/SpineEventEngine/validation/issues/227.
-        // if (boundPrimitive in listOf(UINT32_VALUE, UINT64_VALUE)) {
-        //     unsignedIntegerWarning(view.file, field.span)
-        // }
+        if (boundPrimitive in listOf(UINT32_VALUE, UINT64_VALUE)) {
+            unsignedIntegerWarning(view.file, field.span)
+        }
         return CodeBlock(
             """
             if (${isOutOfBounds(value)}) {
@@ -217,15 +217,16 @@ internal abstract class BoundedFieldGenerator(
     }
 }
 
-@Suppress("unused") // https://github.com/SpineEventEngine/validation/issues/227
 private fun unsignedIntegerWarning(file: File, span: Span) =
-    Compilation.warning(file, span) {
-        "Unsigned integer types are not supported in Java. The Protobuf compiler uses" +
-                " signed integers to represent unsigned types in Java ($SCALAR_TYPES)." +
-                " Operations on unsigned values rely on static utility methods from" +
-                " `$IntegerClass` and `$LongClass` classes ($UNSIGNED_API). Be cautious" +
-                " when dealing with unsigned values outside of these methods, as Java" +
-                " treats all primitive integers as signed."
+    UnsignedIntegerWarnings.report(file, span) {
+        Compilation.warning(file, span) {
+            "Unsigned integer types are not supported in Java. The Protobuf compiler uses" +
+                    " signed integers to represent unsigned types in Java ($SCALAR_TYPES)." +
+                    " Operations on unsigned values rely on static utility methods from" +
+                    " `$IntegerClass` and `$LongClass` classes ($UNSIGNED_API). Be cautious" +
+                    " when dealing with unsigned values outside of these methods, as Java" +
+                    " treats all primitive integers as signed."
+        }
     }
 
 @Suppress("MaxLineLength") // Long links.
@@ -234,3 +235,29 @@ private object Docs {
     const val UNSIGNED_API =
         "https://www.baeldung.com/java-unsigned-arithmetic#the-unsigned-integer-api"
 }
+
+/**
+ * Reports unsigned-integer warnings once per source location.
+ */
+internal object UnsignedIntegerWarnings {
+
+    private val reported = ConcurrentHashMap.newKeySet<String>()
+
+    fun report(file: File, span: Span, warning: () -> Unit) {
+        report(key(file, span), warning)
+    }
+
+    @VisibleForTesting
+    fun report(key: String, warning: () -> Unit) {
+        if (reported.add(key)) {
+            warning()
+        }
+    }
+
+    @VisibleForTesting
+    fun clear() {
+        reported.clear()
+    }
+
+    private fun key(file: File, span: Span): String = "$file:$span"
+}
diff --git a/java/src/test/kotlin/io/spine/tools/validation/java/generate/option/bound/UnsignedIntegerWarningsSpec.kt b/java/src/test/kotlin/io/spine/tools/validation/java/generate/option/bound/UnsignedIntegerWarningsSpec.kt
new file mode 100644
index 0000000000..1c3251ddcb
--- /dev/null
+++ b/java/src/test/kotlin/io/spine/tools/validation/java/generate/option/bound/UnsignedIntegerWarningsSpec.kt
@@ -0,0 +1,69 @@
+/*
+ * Copyright 2026, TeamDev. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package io.spine.tools.validation.java.generate.option.bound
+
+import io.kotest.matchers.shouldBe
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Test
+
+@DisplayName("`UnsignedIntegerWarnings` should")
+internal class UnsignedIntegerWarningsSpec {
+
+    @BeforeEach
+    fun setUp() {
+        UnsignedIntegerWarnings.clear()
+    }
+
+    @Test
+    fun `report warning only once for the same location`() {
+        var reports = 0
+
+        UnsignedIntegerWarnings.report("same-location") {
+            reports++
+        }
+        UnsignedIntegerWarnings.report("same-location") {
+            reports++
+        }
+
+        reports shouldBe 1
+    }
+
+    @Test
+    fun `report warning for each distinct location`() {
+        var reports = 0
+
+        UnsignedIntegerWarnings.report("location-1") {
+            reports++
+        }
+        UnsignedIntegerWarnings.report("location-2") {
+            reports++
+        }
+
+        reports shouldBe 2
+    }
+}
diff --git a/tests/validating/src/test/kotlin/io/spine/test/options/AssumedRequiredITest.kt b/tests/validating/src/test/kotlin/io/spine/test/options/AssumedRequiredITest.kt
index 418344e4fd..015ad04c63 100644
--- a/tests/validating/src/test/kotlin/io/spine/test/options/AssumedRequiredITest.kt
+++ b/tests/validating/src/test/kotlin/io/spine/test/options/AssumedRequiredITest.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright 2024, TeamDev. All rights reserved.
+ * Copyright 2026, TeamDev. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -30,6 +30,7 @@ import io.spine.base.Identifier
 import io.spine.test.tools.validate.TaskId
 import io.spine.test.tools.validate.command.AssignTask
 import io.spine.test.tools.validate.command.CreateProject
+import io.spine.test.tools.validate.entity.NumberStats
 import io.spine.test.tools.validate.entity.Project
 import io.spine.test.tools.validate.entity.Task
 import io.spine.tools.validation.assertions.assertInvalid
@@ -85,5 +86,11 @@ internal class AssumedRequiredITest {
             val msg = Task.newBuilder()
             assertValid(msg)
         }
+
+        @Test
+        fun `not requiring a primitive ID`() {
+            val msg = NumberStats.newBuilder()
+            assertValid(msg)
+        }
     }
 }
diff --git a/tests/validating/src/testFixtures/proto/spine/test/tools/validate/entity.proto b/tests/validating/src/testFixtures/proto/spine/test/tools/validate/entity.proto
index db2d77a63a..b868dc2ee5 100644
--- a/tests/validating/src/testFixtures/proto/spine/test/tools/validate/entity.proto
+++ b/tests/validating/src/testFixtures/proto/spine/test/tools/validate/entity.proto
@@ -1,11 +1,11 @@
 /*
- * Copyright 2024, TeamDev. All rights reserved.
+ * Copyright 2026, TeamDev. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
- * http://www.apache.org/licenses/LICENSE-2.0
+ * https://www.apache.org/licenses/LICENSE-2.0
  *
  * Redistribution and use in source and/or binary forms, with or without
  * modification, must retain the above copyright notice and the following
@@ -23,6 +23,7 @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
+
 syntax = "proto3";
 
 package spine.test.tools.validate;
@@ -52,3 +53,10 @@ message Task {
     // Here the first field (which is assumed to be required) is explicitly set optional.
     string id = 1 [(required) = false];
 }
+
+// An entity type with a primitive ID.
+message NumberStats {
+    option (entity).kind = ENTITY;
+
+    int32 id = 1;
+}
diff --git a/version.gradle.kts b/version.gradle.kts
index ee62bd3168..82a46bd6ca 100644
--- a/version.gradle.kts
+++ b/version.gradle.kts
@@ -27,4 +27,4 @@
 /**
  * The version of the Validation library to publish.
  */
-val validationVersion by extra("2.0.0-SNAPSHOT.420")
+val validationVersion by extra("2.0.0-SNAPSHOT.421")