code: public boolean subtract(String key, ModuleDepInfo subInfo) {
  		boolean modified = false;
  		ModuleDepInfo info = get(key);
  		if (info != null) {
  			modified = info.subtract(subInfo);
  		}
  		return modified;
  	}
docs: Subtracts the terms in <code>subInfo</code> from the terms in the module
  dep info object associated with the specified key.
  <p>
  See {@link ModuleDepInfo#subtract(ModuleDepInfo)} for a description of
  what it means to subtract boolean terms.
  
  @param key
  The module name
  @param subInfo
  The object containing the terms to subtract
  @return true if this map was modified