diff --git a/a2a/pom.xml b/a2a/pom.xml
index c5948508e..8e6c320a8 100644
--- a/a2a/pom.xml
+++ b/a2a/pom.xml
@@ -24,6 +24,9 @@
     <slf4j.version>2.0.17</slf4j.version>
     <truth.version>1.4.4</truth.version>
     <junit4.version>4.13.2</junit4.version>
+    <!-- Load mockito-core as a startup -javaagent so the inline mock maker does not rely on
+         runtime self-attachment, which newer JDKs block. -->
+    <mockito.javaagent.arg>-javaagent:${org.mockito:mockito-core:jar}</mockito.javaagent.arg>
   </properties>
 
   <dependencies>
diff --git a/contrib/firestore-session-service/pom.xml b/contrib/firestore-session-service/pom.xml
index d24ab86f8..fc64812ae 100644
--- a/contrib/firestore-session-service/pom.xml
+++ b/contrib/firestore-session-service/pom.xml
@@ -28,6 +28,11 @@
     <name>Agent Development Kit - Firestore Session Management</name>
     <description>Firestore integration with Agent Development Kit for User Session Management</description>
 
+    <properties>
+        <!-- Load mockito-core as a startup -javaagent so the inline mock maker does not rely
+             on runtime self-attachment, which newer JDKs block. -->
+        <mockito.javaagent.arg>-javaagent:${org.mockito:mockito-core:jar}</mockito.javaagent.arg>
+    </properties>
 
     <dependencies>
 
@@ -90,6 +95,7 @@
                 <artifactId>maven-surefire-plugin</artifactId>
                 <configuration>
                     <argLine>
+                        ${mockito.javaagent.arg}
                         ${jacoco.agent.argLine}
                         --add-opens java.base/java.util=ALL-UNNAMED
                         --add-opens java.base/java.lang=ALL-UNNAMED
diff --git a/contrib/langchain4j/pom.xml b/contrib/langchain4j/pom.xml
index 60f222946..7859fec80 100644
--- a/contrib/langchain4j/pom.xml
+++ b/contrib/langchain4j/pom.xml
@@ -28,6 +28,11 @@
     <name>Agent Development Kit - LangChain4j</name>
     <description>LangChain4j integration for the Agent Development Kit.</description>
 
+    <properties>
+        <!-- Load mockito-core as a startup -javaagent so the inline mock maker does not rely
+             on runtime self-attachment, which newer JDKs block. -->
+        <mockito.javaagent.arg>-javaagent:${org.mockito:mockito-core:jar}</mockito.javaagent.arg>
+    </properties>
 
     <dependencyManagement>
         <dependencies>
diff --git a/contrib/planners/pom.xml b/contrib/planners/pom.xml
index c9dcf6261..3699c1031 100644
--- a/contrib/planners/pom.xml
+++ b/contrib/planners/pom.xml
@@ -28,6 +28,12 @@
     <name>Agent Development Kit - Planners</name>
     <description>Built-in planner implementations for the ADK PlannerAgent, including GOAP (Goal-Oriented Action Planning), P2P (Peer-to-Peer), and Supervisor planners.</description>
 
+    <properties>
+        <!-- Load mockito-core as a startup -javaagent so the inline mock maker does not rely
+             on runtime self-attachment, which newer JDKs block. -->
+        <mockito.javaagent.arg>-javaagent:${org.mockito:mockito-core:jar}</mockito.javaagent.arg>
+    </properties>
+
     <dependencies>
         <!-- Main dependencies -->
         <dependency>
diff --git a/contrib/spring-ai/pom.xml b/contrib/spring-ai/pom.xml
index ca2f0240b..2a6b1143b 100644
--- a/contrib/spring-ai/pom.xml
+++ b/contrib/spring-ai/pom.xml
@@ -31,6 +31,9 @@
     <properties>
         <spring-ai.version>2.0.1</spring-ai.version>
         <testcontainers.version>1.21.3</testcontainers.version>
+        <!-- Load mockito-core as a startup -javaagent so the inline mock maker does not rely
+             on runtime self-attachment, which newer JDKs block. -->
+        <mockito.javaagent.arg>-javaagent:${org.mockito:mockito-core:jar}</mockito.javaagent.arg>
     </properties>
 
     <dependencyManagement>
diff --git a/core/pom.xml b/core/pom.xml
index 82cdb0a9e..86bf91d29 100644
--- a/core/pom.xml
+++ b/core/pom.xml
@@ -27,7 +27,11 @@
   <name>Agent Development Kit</name>
   <description>Agent Development Kit: an open-source, code-first toolkit designed to simplify building, evaluating, and deploying advanced AI agents anywhere.</description>
 
-
+  <properties>
+    <!-- Load mockito-core as a startup -javaagent so the inline mock maker does not rely on
+         runtime self-attachment, which newer JDKs block. -->
+    <mockito.javaagent.arg>-javaagent:${org.mockito:mockito-core:jar}</mockito.javaagent.arg>
+  </properties>
 
   <dependencies>
     <dependency>
diff --git a/dev/pom.xml b/dev/pom.xml
index b27c3b995..10dd4cfda 100644
--- a/dev/pom.xml
+++ b/dev/pom.xml
@@ -25,6 +25,11 @@
   <name>Agent Development Kit - Dev Tools</name>
   <description>Development tools and server for Agent Development Kit.</description>
 
+  <properties>
+    <!-- Load mockito-core as a startup -javaagent so the inline mock maker does not rely on
+         runtime self-attachment, which newer JDKs block. -->
+    <mockito.javaagent.arg>-javaagent:${org.mockito:mockito-core:jar}</mockito.javaagent.arg>
+  </properties>
 
   <dependencyManagement>
     <dependencies>
diff --git a/pom.xml b/pom.xml
index 9a689382e..26e40b432 100644
--- a/pom.xml
+++ b/pom.xml
@@ -77,7 +77,12 @@
     <maven-plugin-tools.version>3.9.0</maven-plugin-tools.version>
     <httpclient5.version>5.6.1</httpclient5.version>
     <netty.version>4.1.118.Final</netty.version>
-    <surefire.argLine>@{jacoco.agent.argLine} --add-opens=java.base/java.nio=ALL-UNNAMED --add-opens=java.base/sun.nio.ch=ALL-UNNAMED --add-opens=java.base/java.util.concurrent=ALL-UNNAMED --add-opens=java.base/java.text=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.lang.reflect=ALL-UNNAMED --add-opens=java.base/jdk.internal.misc=ALL-UNNAMED -Dio.netty.tryReflectionSetAccessible=true</surefire.argLine>
+    <!-- Prepended to the surefire JVM args. Empty by default; any module whose tests resolve
+         mockito-core (directly or transitively) must set it to
+         "-javaagent:${org.mockito:mockito-core:jar}" so the inline mock maker loads as a
+         startup agent instead of self-attaching at runtime, which newer JDKs block. -->
+    <mockito.javaagent.arg></mockito.javaagent.arg>
+    <surefire.argLine>${mockito.javaagent.arg} @{jacoco.agent.argLine} --add-opens=java.base/java.nio=ALL-UNNAMED --add-opens=java.base/sun.nio.ch=ALL-UNNAMED --add-opens=java.base/java.util.concurrent=ALL-UNNAMED --add-opens=java.base/java.text=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.lang.reflect=ALL-UNNAMED --add-opens=java.base/jdk.internal.misc=ALL-UNNAMED -Dio.netty.tryReflectionSetAccessible=true</surefire.argLine>
   </properties>
 
   <dependencyManagement>
@@ -492,6 +497,23 @@
           </execution>
         </executions>
       </plugin>
+      <plugin>
+        <!-- Exposes each resolved dependency's jar path as a ${groupId:artifactId:type}
+             property, so surefire can load mockito-core as a -javaagent (see
+             mockito.javaagent.arg). -->
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-dependency-plugin</artifactId>
+        <version>3.8.1</version>
+        <executions>
+          <execution>
+            <id>resolve-dependency-paths</id>
+            <phase>initialize</phase>
+            <goals>
+              <goal>properties</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
     </plugins>
   </build>
   <profiles>