Command that uses zero or more avro path expressions to extract values from an Avro object.
The Avro input object is expected to be contained in the
Fields.ATTACHMENT_BODY
Each expression consists of a record output field name (on the left side of the colon ':') as
well as zero or more path steps (on the right hand side), each path step separated by a '/'
slash. Avro arrays are traversed with the '[]' notation.
The result of a path expression is a list of objects, each of which is added to the given record
output field.
The path language supports all Avro concepts, including nested structures, records, arrays, maps,
unions, etc, as well as a flatten option that collects the primitives in a subtree into a flat
list.