Build a parameterized build while one or more parameters are empty

[agedio]

I have a project which is a parameterized build. 
For instance I use the following parameters: 

String Parameter 
Name: *WFVERSION*
Default Value: 3.2 

String Parameter 
Name: *WFTESTCYCLE*
Default Value: test 

String Parameter 
Name: *WFBUILDNUMBER*
Default: beta_%{BUILD_NUMBER} 


Then in my pom.xml I catch these parameters to dynamically build the name 
like this: 
  <wf.build.version>*${env.WFVERSION}${env.WFTESTCYCLE}${env.WFBUILDNUMBER}*
</wf.build.version>
  
However sometimes we don't set the WFTESTCYCLE and the WFBUILDNUMBER 
parameters. These values are not always needed. In that case I would like 
the outcome to be: 
<wf.build.version>*3.2*</wf.build.version>

But what happens if you leave the parameterized option *BLANK/EMPTY* is 
this: 
<wf.build.version>*3.2${env.WFTESTCYCLE}${env.WFBUILDNUMBER}*
</wf.build.version>

*So a BLANK/EMPTY parameter results in ${PARAMETER} in my pom.xml. I don't 
want to see the ${PARAMETER} values. It should just be empty. 
Is this possible?*

Thx. 
Hugo