public void setNumThreadsPerSearch(int threads) {
        verifyThat(numThreadsPerSearch == null, "already has num-threads-per-search");
        this.numThreadsPerSearch = threads;
    }
This class holds the extracted information after parsing a
rank-profile block in a schema (.sd) file, using simple data
structures as far as possible.  Do not put advanced logic here!

@author arnej27959
config-model/src/main/java/com/yahoo/schema/parser/ParsedRankProfile.java