ShingleFilterFactory class error

[Pradeep Pujari]

Hi,

I am trying to create shingles with minShingleSize = 10, but it also returns 
bi-grams too. Heres is my schema defn

            <filter class="solr.ShingleFilterFactory" minShingleSize="10" 
maxShingleSize="25"
                outputUnigrams="false" outputUnigramsIfNoShingles="false" 
tokenSeparator=" "/>


For the input String "Apple - iPad 3G Wi-Fi - 32GB", it breaks into
    "Apple -"
    "- iPad "   

My understaing that it should be 10-gram token.

Is it bug or any configuration is to be added. 

Thank you in advance.
Pradeep