The `lib/content-types.properties` file has been removed from the Java run-time image. The `lib/content-types.properties` file contained the default MIME content-types table used to map content type to file extension, etc, and is used primarily by the URLConnection API. The `lib/content-types.properties` file was never intended to be user editable. Instead there is a system property, `content.types.user.table`, that allows one to define their own content types.

See JDK-8039362, for further details on the use of `content.types.user.table`.