private String getEntryAsString(final OptionSpec spec) {
    // returns the string value of the config line corresponding to the option in toml file
    // or null if not present in the config
    return getKeyName(spec).map(result::getString).orElse(null);
  }
Creates a new TomlConfigurationDefaultProvider from an input stream.

@param commandLine the command line
@param inputStream the input stream
@return a new TomlConfigurationDefaultProvider
app/src/main/java/org/hyperledger/besu/cli/util/TomlConfigurationDefaultProvider.java