code: public VCFFormat getFormat(final Path path) {
  		VCFFormat fmt = formatMap.get(path);
  		if (fmt != null || formatMap.containsKey(path))
  			return fmt;
  
  		if (givenMap)
  			throw new IllegalArgumentException(
  				"VCF format for '"+path+"' not in given map");
  
  		if (this.conf == null)
  			throw new IllegalStateException("Don't have a Configuration yet");
  
  		if (trustExts) {
  			final VCFFormat f = VCFFormat.inferFromFilePath(path);
  			if (f != null) {
  
  			    formatMap.put(path, f);
  				return f;
  			}
  		}
  
  		try(InputStream is = path.getFileSystem(conf).open(path)) {
  			fmt = VCFFormat.inferFromData(is);
  		} catch (IOException e) {}
  
  		formatMap.put(path, fmt);
  		return fmt;
  	}
docs: Returns the {@link VCFFormat} corresponding to the given path. Returns
  <code>null</code> if it cannot be determined even based on the file
  contents (unless future VCF/BCF formats are very different, this means
  that the path does not refer to a VCF or BCF file).
  
  <p>If this input format was constructed using a given
  <code>Map&lt;Path,VCFFormat&gt;</code> and the path is not contained
  within that map, throws an {@link IllegalArgumentException}.</p>