Wrong DynamicField type in ES

[lis975]

When you create dynamic filed (DF) type "dropdown list" and set keys and values like this:
key: 2700 value:2700
key: 2201 value:2201
key: 2410 value:2410
key: 2511 value: 2511
e.t.c.
and finally last pair of data:
key: nd value: nd

If you create in ES the new ticket index and send tickets data to build it this happens:

• if the first DF occurrence in ticket sent to ES has numeric value/key: the field in ES is recognized as type DATE.
• If first DF occurrence in ticket has value/key "nd" the ES field type is recognized as text.
  The problem is, that when ES sets field type to date (incorrect), the value/key "nd" causes an error because "nd" cannot be converted to date type.