GenerateTableFetch produces SQLException when table is empty

When GenerateTableFetch executes with the following conditions ...

1. partition size = 0
2. max value columns are unset
3. connecting to MS SQL Server
4. the target table has 0 rows

... the processor throws a SQLException "Unable to execute SQL select query SELECT -1 FROM [mydb].[dbo].[tbl_test_01] due to java.sql.SQLException: No rows returned from metadata query: SELECT -1 FROM [mydb].[dbo].[tbl_test_01]" and rolls back the flow file. 

The issue appears to be introduced in the fix for https://issues.apache.org/jira/browse/NIFI-5855 when -1 was used in place of "COUNT( * )".  For an empty table, the SQL Server driver returns 0 rows for the query "SELECT -1 FROM <table>".  GenerateTableFetch throws a SQLException when the resultset contains 0 rows.

Version details:

MS SQL Server: 12.0.6108.1

JDBC Driver: com.microsoft.sqlserver:mssql-jdbc:7.4.1.jre8

JDBC Class: com.microsoft.sqlserver.jdbc.SQLServerDriver

Edit: 4/30/2020: After further testing, I have replicated this behavior with postgres:8.4 and mysql:8.0.13