[Gradle] A version error instance (Could not find xxx)

The build.gradle configuration, because spring uses a lot of packages, the version number is uniformly configured, as follows:

ext{
    springVersion = '4.3.13.RELEASE'
}

dependencies {

    compile group: 'org.springframework', name: 'spring-webmvc', version: springVersion
    compile group: 'org.springframework', name: 'spring-jdbc', version: springVersion
    compile group: 'org.springframework', name: 'spring-web', version: springVersion

//...
    compile group: 'org.apache.tomcat', name: 'tomcat-servlet-api', version: springVersion

}

I get an error when compiling:

Warning:<i><b>root project 'Mattrack': Web Facets/Artifacts will not be configured properly</b>
Details: org.gradle.api.internal.artifacts.ivyservice.DefaultLenientConfiguration$ArtifactResolveException: Could not resolve all files for configuration ':runtimeClasspath'.
Caused by: org.gradle.internal.resolve.ModuleVersionNotFoundException: Could not find org.apache.tomcat:tomcat-servlet-api:4.3.13.RELEASE.
Required by:
    project :</i>

Note here: Could not find org.apache.tomcat:tomcat-servlet-api:4.3.13.RELEASE. It
　　means that "org.apache.tomcat:tomcat-servlet-api:4.3.13.RELEASE" could not be
found build.gradle, found that 'tomcat-servlet-api' uses the wrong version of Spring.