Field name cannot contain '.'

[3ygun]

For anyone looking into this here is the current state:

• **'.'**s can be used in Logstash
• **'.'**s cannot be used in Elasticsearch 2.X
  • ES issue
• **BUT '.'**s should be usable in Elasticsearch 5.X
  • '.'s in Dynamic Mappings
  • '.'s in Specific Mappings

Best of luck!