Defining and assigning maven propertiy value

I need to assign value to a maven property using Gradle

in my app in the pom.xml file the property value has been defined by

<app.version>2012.5.0</app.version>

how can i define this value in gradle’s build.gradle so that its value could be accessed to an another pom.xml file

through

the keyword

${app.version}

anybody please reply