@Override
	public boolean isValid(TaskMonitor monitor) {
		// NOTE: checking a http symbolserver's state by testing the
		// existence of a file is not 100% universally correct, as different
		// webserver implementations will handle this differently, but
		// no better options are apparent.
		// Just getting any HTTP response, including a 404 not found, isn't a
		// good indication that the symbol server is valid as it could be
		// a missing subtree of a parent web site.
		return exists("", monitor) || exists(PINGME_FILENAME, monitor);
	}
Creates a new instance of a HttpSymbolServer.

@param serverURI URI / URL of the symbol server 
@param isTrusted flag, if true the http server can be trusted when querying and downloading
Ghidra/Features/PDB/src/main/java/pdb/symbolserver/HttpSymbolServer.java