Nifi PutKudu processor - Convert record field names to lowercase

Kudu supports case sensitive column names while query tools built over Kudu (eg. Impala) do not. If a table is created via Impala, which is the most common use case, all column names are converted to lowercase. If an incoming record in a FlowFile contains uppercase column names, the columns won't match the schema of the destination table unless the schema for the record is modified to have lowercase field names.

Rather than converting the schema of the record, I propose field names are converted to lowercase before they are put into Kudu.