diff --git a/lab-39/lab-39-async/pom.xml b/lab-39/lab-39-async/pom.xml
index 82cdd5a5..2e71a62c 100644
--- a/lab-39/lab-39-async/pom.xml
+++ b/lab-39/lab-39-async/pom.xml
@@ -9,7 +9,6 @@
         <relativePath/> <!-- lookup parent from repository -->
     </parent>
     <modelVersion>4.0.0</modelVersion>
-    <packaging>jar</packaging>
 
     <artifactId>lab-39-async</artifactId>
 
diff --git a/lab-39/lab-39-logback/pom.xml b/lab-39/lab-39-logback/pom.xml
index 56d887e6..d09e763b 100644
--- a/lab-39/lab-39-logback/pom.xml
+++ b/lab-39/lab-39-logback/pom.xml
@@ -9,7 +9,6 @@
         <relativePath/> <!-- lookup parent from repository -->
     </parent>
     <modelVersion>4.0.0</modelVersion>
-    <packaging>jar</packaging>
 
     <artifactId>lab-39-logback</artifactId>
 
diff --git a/lab-39/lab-39-springmvc/pom.xml b/lab-39/lab-39-springmvc/pom.xml
index 8241d0b8..a8d0909b 100644
--- a/lab-39/lab-39-springmvc/pom.xml
+++ b/lab-39/lab-39-springmvc/pom.xml
@@ -9,7 +9,6 @@
         <relativePath/> <!-- lookup parent from repository -->
     </parent>
     <modelVersion>4.0.0</modelVersion>
-    <packaging>jar</packaging>
 
     <artifactId>lab-39-springmvc</artifactId>
 
diff --git a/lab-39/lab-39-trace-annotations/pom.xml b/lab-39/lab-39-trace-annotations/pom.xml
index a3ca1e63..31ffb007 100644
--- a/lab-39/lab-39-trace-annotations/pom.xml
+++ b/lab-39/lab-39-trace-annotations/pom.xml
@@ -9,7 +9,6 @@
         <relativePath/> <!-- lookup parent from repository -->
     </parent>
     <modelVersion>4.0.0</modelVersion>
-    <packaging>jar</packaging>
 
     <artifactId>lab-39-trace-annotations</artifactId>