diff --git a/pom/src/plugin-resources/xsd/pom-strict-3.xsd b/pom/src/plugin-resources/xsd/pom-strict-3.xsd
index 98eb977a..4f1045e0 100644
--- a/pom/src/plugin-resources/xsd/pom-strict-3.xsd
+++ b/pom/src/plugin-resources/xsd/pom-strict-3.xsd
@@ -295,7 +295,7 @@
 
         <xs:complexType>
           <xs:sequence>
-            <xs:element minOccurs="0" maxOccurs="unbounded" name="developer"
+            <xs:element minOccurs="1" maxOccurs="unbounded" name="developer"
                         type="Developer"/>
           </xs:sequence>
         </xs:complexType>
@@ -313,7 +313,7 @@
 
         <xs:complexType>
           <xs:sequence>
-            <xs:element minOccurs="0" maxOccurs="unbounded" name="contributor"
+            <xs:element minOccurs="1" maxOccurs="unbounded" name="contributor"
                         type="Contributor"/>
           </xs:sequence>
         </xs:complexType>
@@ -372,7 +372,7 @@
 
         <xs:complexType>
           <xs:sequence>
-            <xs:element maxOccurs="unbounded" name="branch"
+            <xs:element minOccurs="1" maxOccurs="unbounded" name="branch"
                         type="Branch"/>
           </xs:sequence>
         </xs:complexType>