Jmeter remove empty strings at a SOAP/xml reqeust

I am using "Jmeter with CSV and SOAP/xml request". My tests are running within like 80 data sets and some fields in the CSV must be empty for testing issues.

My JMeter Build: -ThreadGroup -CSV Data -SOAP/XML -XPathExtractor -Outcome

CSV like a matrix table, multiple rows and columns.

SOAP/XML

...
<attribute xsi:type="ns2:stringType" name = "freeText2">
<value>${freeText2}</value>
</attribute>
<attribute xsi:type="ns2:longType" name = "amount">
<value>${amount}</value>
</attribute>
...

My Problem: When Jmeter has replaced the varibles:

<attribute xsi:type="ns2:stringType" name = "freeText2">
<value>This is my free Text</value>
</attribute>
<attribute xsi:type="ns2:longType" name = "amount">
<value>455667</value>
</attribute>

ALL IS FINE BUT when some are empty

<attribute xsi:type="ns2:stringType" name = "freeText2">
<value></value> ==>interpreted as STRING
</attribute>
<attribute xsi:type="ns2:longType" name = "amount">
<value></value> ==>interpreted as STRING
</attribute>

The System tells me that "Long Amount with "" is not possible" and also i dont want to have in my System a freeText2 with "" empty String.

Now my Question: Is there any way to wirte a adapter/handler/extractor...anything to get the Request empty String converted just to nothing (not Null because it will throw me a NullPointerException) like ==>

<attribute xsi:type="ns2:longType" name = "amount">
<value></value>
</attribute>

converted to

<attribute xsi:type="ns2:longType" name = "amount">

</attribute>

I hope you can help me with my issue, best regards, Daniel