Collection the data metrics where there are unique keys

The script failed, elapsed time: 0 seconds - Cannot invoke method tokenize() on null object
java.lang.NullPointerException: Cannot invoke method tokenize() on null object
    at org.codehaus.groovy.runtime.NullObject.invokeMethod(NullObject.java:91)
    at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:47)
    at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47)
    at org.codehaus.groovy.runtime.callsite.NullCallSite.call(NullCallSite.java:34)
    at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:116)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:128)
    at Script1309$_run_closure2.doCall(Script1309.groovy:36)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorIm