Displaying custom data into the SIEM map

Hi im trying to display data in the SIEM map, using ECS, Im getting the data from a database using logstash JDBC

this is the template for the index

PUT _template/ecs
  "mappings": {
    "properties": {
      "@timestamp": {
        "type": "date"
      "destination.geo": {
        "type": "geo_point"
      "source.geo": {
        "type": "geo_point"
  "index_patterns": [

and this is what I have tried to do in logstash to set the fields

add_field => { "[source][geo][location][lat]" => "%{src_lat}"}}
add_field => { "[source][geo][location][lon]" => "%{src_long}"}}
add_field => { "[destination][geo][location][lat]" => "%{dest_lat}"}}
 add_field => { "[destination][geo][location][lon]" => "%{dest_long}"}}

and logstash gives me this error: "field must be either [lat], [lon] or [geohash]"

I also tried to put this as a string in the pipeline:

add_field => { "[destination][geo][location]" => "%{dest_lat}, %{dest_long}"}}}

and as an array:

add_field => { "[destination][geo][location]" => ["%{dest_lat}", "%{dest_long}"]}}

but all of the above gives me te error "field must be either [lat], [lon] or [geohash]"

how can i solve this?