Allow port=0 in XSD

Issue gh-8138

config/src/main/resources/org/springframework/security/config/spring-security-5.4.rnc

@@ -16,7 +16,7 @@ request-matcher =
 	attribute request-matcher {"mvc" | "ant" | "regex" | "ciRegex"}
 port =
 	## Specifies an IP port number. Used to configure an embedded LDAP server, for example.
-	attribute port { xsd:positiveInteger }
+	attribute port { xsd:nonNegativeInteger }
 url =
 	## Specifies a URL.
 	attribute url { xsd:token }

config/src/main/resources/org/springframework/security/config/spring-security-5.4.xsd

@@ -43,7 +43,7 @@
       </xs:attribute>
   </xs:attributeGroup>
   <xs:attributeGroup name="port">
-      <xs:attribute name="port" use="required" type="xs:positiveInteger">
+      <xs:attribute name="port" use="required" type="xs:nonNegativeInteger">
          <xs:annotation>
             <xs:documentation>Specifies an IP port number. Used to configure an embedded LDAP server, for example.
                 </xs:documentation>
@@ -190,7 +190,7 @@
                 </xs:documentation>
          </xs:annotation>
       </xs:attribute>
-      <xs:attribute name="port" type="xs:positiveInteger">
+      <xs:attribute name="port" type="xs:nonNegativeInteger">
          <xs:annotation>
             <xs:documentation>Specifies an IP port number. Used to configure an embedded LDAP server, for example.
                 </xs:documentation>