Avoid type pollution in StringCollectionDeserializer

pom.xml

@@ -154,6 +154,22 @@
       <version>${version.mockito}</version>
       <scope>test</scope>
     </dependency>
+
+    <!-- Dependencies for testing "type pollution", see:
+         https://github.com/FasterXML/jackson-databind/pull/4848
+      -->
+    <dependency>
+      <groupId>org.junit.platform</groupId>
+      <artifactId>junit-platform-suite-engine</artifactId>
+      <version>1.10.2</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>io.micronaut.test</groupId>
+      <artifactId>micronaut-test-type-pollution</artifactId>
+      <version>4.6.2</version>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 
   <!-- Alas, need to include snapshot reference since otherwise can not find
@@ -213,6 +229,7 @@
           <excludes>
             <exclude>com.fasterxml.jackson.databind.MapperFootprintTest</exclude>
           </excludes>
+          <test>com.fasterxml.jackson.databind.PrimarySuite</test>
           <!-- 26-Nov-2019, tatu: moar parallelism! Per-class basis, safe, efficient enough
                   ... although not 100% sure this makes much difference TBH
             -->
@@ -386,6 +403,19 @@
             <configuration>
               <argLine>--add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED</argLine>
             </configuration>
+            <executions>
+              <execution>
+                <id>type-pollution-test</id>
+                <phase>test</phase>
+                <goals>
+                  <goal>test</goal>
+                </goals>
+                <configuration>
+                  <test>com.fasterxml.jackson.databind.typepollution.TypePollutionSuite</test>
+                  <threadCount>1</threadCount>
+                </configuration>
+              </execution>
+            </executions>
           </plugin>
         </plugins>
       </build>

src/test-jdk17/java/com/fasterxml/jackson/databind/typepollution/TypePollutionSuite.java

@@ -0,0 +1,9 @@
+package com.fasterxml.jackson.databind.typepollution;
+
+import org.junit.platform.suite.api.SelectPackages;
+import org.junit.platform.suite.api.Suite;
+
+@Suite
+@SelectPackages("com.fasterxml.jackson.databind.typepollution")
+public class TypePollutionSuite {
+}

src/test-jdk17/java/com/fasterxml/jackson/databind/typepollution/TypePollutionTest.java

@@ -0,0 +1,91 @@
+package com.fasterxml.jackson.databind.typepollution;
+
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import io.micronaut.test.typepollution.FocusListener;
+import io.micronaut.test.typepollution.ThresholdFocusListener;
+import io.micronaut.test.typepollution.TypePollutionTransformer;
+import org.junit.jupiter.api.*;
+import org.junit.jupiter.api.function.Executable;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.json.JsonMapper;
+
+public class TypePollutionTest {
+    private static final int THRESHOLD = 1000;
+    private ThresholdFocusListener focusListener;
+
+    @BeforeAll
+    static void setupAgent() {
+        TypePollutionTransformer.install(net.bytebuddy.agent.ByteBuddyAgent.install());
+    }
+
+    @BeforeEach
+    void setUp() {
+        focusListener = new ThresholdFocusListener();
+        FocusListener.setFocusListener(focusListener);
+    }
+
+    @AfterEach
+    void verifyNoTypeThrashing() {
+        FocusListener.setFocusListener(null);
+        Assertions.assertTrue(focusListener.checkThresholds(THRESHOLD), "Threshold exceeded, check logs.");
+    }
+
+    private void doTest(Executable r) throws Throwable {
+        for (int i = 0; i < THRESHOLD * 2; i++) {
+            r.execute();
+        }
+    }
+
+    @Test
+    @Disabled
+    public void sample() throws Throwable {
+        // example test. If you enable this, it will fail, and you can see what a type pollution error looks like.
+
+        interface A {
+        }
+
+        interface B {
+        }
+
+        class Concrete implements A, B {
+        }
+
+        Object c = new Concrete();
+        AtomicInteger j = new AtomicInteger();
+        doTest(() -> {
+            if (c instanceof A) {
+                j.incrementAndGet();
+            }
+            if (c instanceof B) {
+                j.incrementAndGet();
+            }
+        });
+        System.out.println(j);
+    }
+
+    @Test
+    public void deserializeRecordWithList() throws Throwable {
+        ObjectMapper mapper = JsonMapper.builder().build();
+        ListRecord input = new ListRecord(List.of("foo"));
+        String json = mapper.writeValueAsString(input);
+        doTest(() -> Assertions.assertEquals(input, mapper.readValue(json, ListRecord.class)));
+    }
+
+    record ListRecord(List<String> list) {
+    }
+
+    @Test
+    public void deserializeRecordWithSet() throws Throwable {
+        ObjectMapper mapper = JsonMapper.builder().build();
+        SetRecord input = new SetRecord(Set.of("foo"));
+        String json = mapper.writeValueAsString(input);
+        doTest(() -> Assertions.assertEquals(input, mapper.readValue(json, SetRecord.class)));
+    }
+
+    record SetRecord(Set<String> list) {
+    }
+}

src/test/java/com/fasterxml/jackson/databind/PrimarySuite.java

@@ -0,0 +1,15 @@
+package com.fasterxml.jackson.databind;
+
+import org.junit.platform.suite.api.ExcludeClassNamePatterns;
+import org.junit.platform.suite.api.ExcludePackages;
+import org.junit.platform.suite.api.SelectPackages;
+import org.junit.platform.suite.api.Suite;
+
+@Suite
+@SelectPackages("com.fasterxml.jackson.databind")
+@ExcludePackages("com.fasterxml.jackson.databind.typepollution")
+@ExcludeClassNamePatterns({
+        "com\\.fasterxml\\.jackson\\.databind\\.MapperFootprintTest"
+})
+public class PrimarySuite {
+}