(doc) Use hyphen instead of null for empty value

For other empty value we use `-` so follow convention

src/site/markdown/configuration.md

@@ -34,7 +34,7 @@ Option | Type | Description | Default Value | Supports Repo ID Suffix
 `aether.connector.basic.parallelPut` | boolean | Enables or disables parallel PUT processing (parallel deploys) on basic connector globally or per remote repository. When disabled, connector behaves exactly as in Maven 3.8.x did: GETs are parallel while PUTs are sequential. | `true` | yes
 `aether.connector.classpath.loader` | ClassLoader | `ClassLoader` from which resources should be retrieved which start with the `classpath:` protocol. | `Thread.currentThread().getContextClassLoader()` | no
 `aether.connector.connectTimeout` | long | Connect timeout in milliseconds. | `10000` | yes
-`aether.connector.http.bind.address` | String | Set the outgoing interface (globally or per remote repository). Valid values are local accessible IP addresses or host names. The default will use the system's default route. Invalid addresses will result in HttpTransport creation failure. | `null` | yes
+`aether.connector.http.bind.address` | String | Set the outgoing interface (globally or per remote repository). Valid values are local accessible IP addresses or host names. The default will use the system's default route. Invalid addresses will result in HttpTransport creation failure. | - | yes
 `aether.connector.http.cacheState` | boolean | Flag indicating whether a memory-based cache is used for user tokens, connection managers, expect continue requests and authentication schemes. | `true` | no
 `aether.connector.http.connectionMaxTtl` | int | Total time to live in seconds for an HTTP connection, after that time, the connection will be dropped (no matter for how long it was idle). | `300` | yes
 `aether.connector.http.credentialEncoding` | String | The encoding/charset to use when exchanging credentials with HTTP servers. | `"ISO-8859-1"` | yes