For analytics, here's an easy and elegant way to devide numeric value (document size in this case) to groups of ranges using Groovy.

sizeGroupAnalytics.groovy

long contentLength = doc.getContentLength() // never mind where the long value comes from.

// Classify doc size. Notice that numbers in map's key have to be ordered (TreeMap) and last key should be Integer.MAX_VALUE:
// This is map of max length size value to a string describing this group
def docGroupMap = new TreeMap([2048:'0-2 KB', 5120:'2-5 KB', 10240:'5-10 KB', (Integer.MAX_VALUE): '10+ KB'])


// The find() method iterates the map and checks every key with the expression in its closure-parameter.
// Since TreeMap is used, the keys are ordered.
// Once the expression is true, the value is being assigned to the string. 
// The value is a string describing textually the document size group.
String docSizeGroup = docGroupMap.find{k,v -> 
    contentLength < k 
}.value