[SQL] How to get an encoder for string array in java?
I'm trying to implement org.apache.spark.sql.expressions.Aggregator in java.
Both the input and output columns are arrays of strings. I can not figure
out how to construct a working encoder for the method outputEncoder() and
for the UDF registration. The data type on java side could be
Collection<String> or String or something equivalent.
Encoders.bean does not work, because array is not struct type (throws
Encoders.kyro does not work because the data types on spark side do not
match (array<String> vs binary)