parsing json via Groovy in soapui

The JSON Data is a response of a rest service(list_files)

{"Files": [
   {"filepath": "input/file_29112017d.csv"},
   {"filepath": "input/file_29112017d.log"},
   {"filepath": "input/file_29112017d.ini"},
   {"filepath": "output/file_29112017d.xml"},
   {"filepath": "output/file_29112017d.csv.trc"}
]}

The goal is to get the path of csv file and not *csv.trc. Also the order of response varies with each test runs i.e 

$.Files[*].filepath[0] does not yield always

input/file_29112017d.csv

This doesn't work either 

import static com.jayway.jsonpath.JsonPath.parse

def response = context.expand( '${list_files#Response}' )
//log.info response gives correctly
def csvpath= parse(response).read('$.Files[?(@.filepath =~ /.*csv/i)]')
log.info csvpath

the error is 

Wed Nov 29 17:06:54 CET 2017:ERROR:java.lang.IllegalArgumentException: Unsupported operator =
   java.lang.IllegalArgumentException: Unsupported operator =
   	at com.jayway.jsonpath.internal.filter.eval.ExpressionEvaluator.eval(ExpressionEvaluator.java:65)
   	at com.jayway.jsonpath.internal.filter.ArrayEvalFilter.isMatch(ArrayEvalFilter.java:90)
   	at com.jayway.jsonpath.internal.filter.ArrayEvalFilter.filter(ArrayEvalFilter.java:69)
   	at com.jayway.jsonpath.internal.filter.PathTokenFilter.filter(PathTokenFilter.java:50)
   	at com.jayway.jsonpath.JsonPath.read(JsonPath.java:255)
   	at com.jayway.jsonpath.internal.JsonReader.read(JsonReader.java:103)
   	at com.jayway.jsonpath.internal.JsonReader.read(JsonReader.java:97)
   	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
   	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
   	at java.lang.reflect.Method.invoke(Unknown Source)
   	at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoCachedMethodSite.invoke(PojoMetaMethodSite.java:189)
   	at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite.call(PojoMetaMethodSite.java:53)
   	at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:45)
   	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:108)
   	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:116)
   	at Script12.run(Script12.groovy:5)
   	at com.eviware.soapui.support.scripting.groovy.SoapUIGroovyScriptEngine.run(SoapUIGroovyScriptEngine.java:90)
   	at com.eviware.soapui.impl.wsdl.teststeps.WsdlGroovyScriptTestStep.run(WsdlGroovyScriptTestStep.java:141)
   	at com.eviware.soapui.impl.wsdl.panels.teststeps.GroovyScriptStepDesktopPanel$RunAction$1.run(GroovyScriptStepDesktopPanel.java:250)
   	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
   	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
   	at java.lang.Thread.run(Unknown Source)