We have a [JsonDecoder](https://github.com/metafacture/metafacture-core/blob/master/metafacture-json/src/main/java/org/metafacture/json/JsonDecoder.java), but [no Flux command](https://github.com/metafacture/metafacture-core/blob/master/metafacture-json/src/main/resources/flux-commands.properties) is defined, should be `decode-json`. See also https://github.com/hbz/oerindex/issues/3.