Maven: CXF exclude Spring - maven

Question

I have CXF 3.0.4, but I'm getting some warnings in my build that it's looking for Spring 3.2.6.RELEASE jars. We're currently using Spring 4.0.5.
The build is working fine, but I'm just trying to get rid of the warning messages.
<artifactId>cxf-codegen-plugin</artifactId>
<groupId>${org.apache.cxf.groupId}</groupId>
<version>${cxf.version}</version>
<configuration>
<excludes>
<exclude>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>3.2.6.RELEASE</version>
</exclude>
<exclude>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>3.2.6.RELEASE</version>
</exclude>
<exclude>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>3.2.6.RELEASE</version>
</exclude>
<exclude>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>3.2.6.RELEASE</version>
</exclude>
<exclude>
<groupId>org.springframework</groupId>
<artifactId>spring-expression</artifactId>
<version>3.2.6.RELEASE</version>
</exclude>
</excludes>
</configuration>
That's what I've specified in the pom, but I'm seeing this as an error
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Failed to configure plugin parameters for: org.apache.cxf:cxf-codegen-plugin:3.0.4
Cause: When configuring a basic element the configuration cannot contain any child elements. Configuration element 'exclude'.
[INFO] ------------------------------------------------------------------------
[DEBUG] Trace
org.apache.maven.lifecycle.LifecycleExecutionException: Error configuring: org.apache.cxf:cxf-codegen-plugin. Reason: Unable to parse the created DOM for plugin configuration
What am I doing wrong here? The file structure of the jar has the plugin.xml in the META-INF/maven directory, and the dependencies are listed there clearly. I tried excluding at a dependency, rather than plugin level, and I got the following warnings.
[INFO] --- cxf-codegen-plugin:3.0.4:wsdl2java (generate-sources) # generated ---
[WARNING] The POM for org.springframework:spring-core:jar:3.2.6.RELEASE is missing, no dependency information available
[WARNING] The POM for org.springframework:spring-aop:jar:3.2.6.RELEASE is missing, no dependency information available
[WARNING] The POM for org.springframework:spring-beans:jar:3.2.6.RELEASE is missing, no dependency information available
[WARNING] The POM for junit:junit:jar:4.12 is missing, no dependency information available
[WARNING] The POM for com.sun.xml.bind:jaxb-xjc:jar:2.2.11 is missing, no dependency information available

Answer 1

As you can see in cxf-codgen-plugin POM:
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<optional>true</optional>
</dependency>
all Spring dependencies are optional. Maven should not load Spring dependencies in your Maven project, see Optional Dependencies and Dependency Exclusions:
If a user wants to use functionality related to an optional dependency, they will have to redeclare that optional dependency in their own project.