public static FetchVector fromMap(Map<Dimension, String> map) {
        return new FetchVector(map);
    }
Denotes which RawFlag should be retrieved from {@link FlagSource} for a given {@link FlagId},
as the raw flag may depend on the hostname, application, etc.

@author hakonhall
flags/src/main/java/com/yahoo/vespa/flags/FetchVector.java