code: public synchronized void addStratum(SmapStratum stratum, boolean defaultStratum) {
          strata.add(stratum);
          if (defaultStratum)
              this.defaultStratum = stratum.getStratumName();
      }
docs: Adds the given SmapStratum object, representing a Stratum with
  logically associated FileSection and LineSection blocks, to
  the current SmapGenerator.  If <tt>default</tt> is true, this
  stratum is made the default stratum, overriding any previously
  set default.
  
  @param stratum the SmapStratum object to add
  @param defaultStratum if <tt>true</tt>, this SmapStratum is considered
  to represent the default SMAP stratum unless
  overwritten