You can have the property default value defined in <build>/<properties>
or in a profile like shown below. When you supply the property value on command line with -DmyProperty=anotherValue
then it will override the definition from the POM. That is, all definitions of property values in the POM are set only a default value for the properties.
<profile>
...
<properties>
<myProperty>defaultValue</myProperty>
</properties>
...
<configuration>
<param>${myProperty}</param>
</configuration>
...
</profile>