Update ngsi_arcgis_featuretable_sink.md

doc/cygnus-ngsi/flume_extensions_catalogue/ngsi_arcgis_featuretable_sink.md

@@ -11,6 +11,8 @@ Content:
     * [Configuration](#section2.1)
     * [Important notes](#section2.2)
         * [About batching](#section2.2.1)
+        * [About case-sensitivity](#section2.2.2)
+        * [About Arcgis data types](#section2.2.3)
 * [Programmers guide](#section3)
     * [`NGSIArcgisFeatureTableSink` class](#section3.1)
     * [Authentication and authorization](#section3.2)
@@ -42,7 +44,7 @@ Each entity type needs an url and an unique field to be persisted into the featu
 
 NGSIArcgisFeatureTableSink composes each table's url with entitie's `service` and `service path`, to provide multiple tables access. 
 
-Unique field is provided to allow `NGSIArcgisFeatureTableSink` to update existant entities. NGSI `entity type` will be used as unique field name.
+Unique field is provided to allow `NGSIArcgisFeatureTableSink` to update existant entities. NGSI `entity type` will be used as unique field name. This means that a feature named `type` in the Feature Table cannot be filled in by the sink. If Feature Table needs to persist the value of entity type it has to be in a feature different than `type`.
 
 All this parameters, can be customized using Cygnus mapping capabilities.
 
@@ -133,7 +135,6 @@ A configuration example could be:
     cygnus-ngsi.sinks.arcgis-sink.type = com.telefonica.iot.cygnus.sinks.NGSIArcgisFeatureTableSink
     cygnus-ngsi.sinks.arcgis-sink.channel = arcgis-channel
     cygnus-ngsi.sinks.arcgis-sink.enable_name_mappings = true
-    cygnus-ngsi.sinks.arcgis-sink.enable_name_mappings = false
     cygnus-ngsi.sinks.arcgis-sink.arcgis_service_url = https://arcgis.com/UsuarioArcgis/arcgis/rest/services
     cygnus-ngsi.sinks.arcgis-sink.arcgis_username = myuser
     cygnus-ngsi.sinks.arcgis-sink.arcgis_password = mypassword
@@ -160,6 +161,20 @@ Connections to `cygnus-ngsi.sinks.arcgis-sink.arcgis_service_url` and `cygnus-ng
 
 [Top](#top)
 
+#### <a name="section2.2.2"></a>About case-sensitivity
+
+**[FIXME #2320](https://github.com/telefonicaid/fiware-cygnus/issues/2320)**. Currently Arcgis sink is case sensitive with the attributes to persist in the Feature Table although arcgis is not case sensitive. This behaviour requires the use of name-mappings to match the case letters of the attribute definition in the Feature Table.
+
+[Top](#top)
+
+#### <a name="section2.2.3"></a>About Arcgis data types
+
+- **esriFieldTypeDate**
+
+From https://doc.arcgis.com/en/data-pipelines/latest/process/output-feature-layer.htm
+> ... Date fields are stored in feature layers using the format milliseconds from epoch and the coordinated universal time (UTC) time zone. The values will be displayed differently depending on where you are viewing the data. For example, querying the feature service REST end point will return values in milliseconds from epoch, such as 1667411518878....
+
+So, to persist a `esriFieldTypeDate` field in the Feature Layer, cygnus has to receive an attribute "Number" from the CB with the milliseconds from epoch.
 
 ## <a name="section3"></a>Programmers guide
 ### <a name="section3.1"></a>`NGSIArcgisFeatureTableSink` class