checkArgument(type != implementation, "Don't register %s to itself!", type);
    checkArgument(
        !DEFAULTS.containsKey(type), "A default value was already registered for %s", type);
    checkArgument(
        implementations.put(type, implementation) == null,
        "Implementation for %s was already registered",
        type);
  }

  static {
    setImplementation(Appendable.class, StringBuilder.class);

        // Test that "yes" string defaults to false (not a valid boolean)
        Map<String, Object> properties = Map.of(Constants.MAVEN_DEPLOY_BUILD_POM, "yes");
        assertFalse(Features.deployBuildPom(properties));
    }

    @Test
    void testDeployBuildPomWithNumericString() {
        // Test that numeric string defaults to false

     * Interpolates the values in the given map using the provided callback function.
     * This method defaults to setting empty strings for unresolved placeholders.
     *
     * @param properties The map containing key-value pairs to be interpolated.
     * @param callback The function to resolve variable values not found in the map.
     */
    default void interpolate(@Nonnull Map<String, String> properties, @Nullable UnaryOperator<String> callback) {

     * The default value is {@code "main"}.
     *
     * @see ProjectScope#MAIN
     */
    default ProjectScope scope() {
        return ProjectScope.MAIN;
    }

    /**
     * {@return the language of the source files}.
     * The default value is {@code "java"}.
     *
     * @see Language#JAVA_FAMILY
     */
    default Language language() {

sasl_mechanism   (string)    sasl authentication mechanism, default 'plain'
tls_client_auth  (string)    clientAuth determines the Kafka server's policy for TLS client auth
sasl             (on|off)    set to 'on' to enable SASL authentication
tls              (on|off)    set to 'on' to enable TLS
tls_skip_verify  (on|off)    trust server TLS without verification, defaults to "on" (verify)

    /** Whether to convert DFS paths to FQDN */
    protected boolean dfsConvertToFqdn;
    /** Default logon share */
    protected String logonShare;
    /** Default domain for authentication */
    protected String defaultDomain;
    /** Default username for authentication */
    protected String defaultUserName;
    /** Default password for authentication */
    protected String defaultPassword;
    /** NetBIOS hostname */

# This file contains the initial defaults for go command configuration.
# Values set by 'go env -w' and written to the user's go/env file override these.
# The environment overrides everything else.

# Use the Go module mirror and checksum database by default.
# See https://proxy.golang.org for details.
GOPROXY=https://proxy.golang.org,direct
GOSUMDB=sum.golang.org

# Automatically download newer toolchains as directed by go.mod files.

# End of variables that can be overwritten in $DEFAULT

# overwrite settings from default file
if [ -f "$DEFAULT" ]; then
	. "$DEFAULT"
fi

# Define other required variables
PID_FILE="$PID_DIR/$NAME.pid"
DAEMON=$FESS_HOME/bin/fess
DAEMON_OPTS="-d -p $PID_FILE --default.path.conf=$CONF_DIR --default.path.home=$FESS_HOME --default.path.logs=$LOG_DIR --default.path.data=$DATA_DIR"

export FESS_HEAP_SIZE

                setDefaultProperties();
            }
        } catch (IOException e) {
            logger.warn("Failed to load system.properties, using defaults", e);
            setDefaultProperties();
        }
    }

    private void setDefaultProperties() {
        // Set default test properties
        setProperty("fess.version", "99.99.99");
    }

    /** Default interval time in milliseconds for web crawling. */
    public static final int DEFAULT_INTERVAL_TIME_FOR_WEB = 10000;

    /** Default number of threads for file system crawling. */
    public static final int DEFAULT_NUM_OF_THREAD_FOR_FS = 5;

    /** Default number of threads for web crawling. */
    public static final int DEFAULT_NUM_OF_THREAD_FOR_WEB = 1;