getColumnNames(Sheet sheet) → UnsupportedOperationException: Getting row by index not supported when streaming.

[adrian-pusty]

Is it expected behaviour that using StreamingXlsxItemReader with BeanWrapperRowMapper causes UnsupportedOperationException?

StreamingSheet throws (in method: getRow(int rowNumber)) this exception when we try to retrieve column names.

I have a sample code snippet that reproduces this issue: https://github.com/adrian-pusty/spring-batch-extensions/commit/8c1f3baa74b455ee14cd20468b7299a898a571bc#diff-e8b601a5301d162b2c94ad1fed7ab3dcc638bd4d49eed4dff61db1074ae3a037

I think that having "header" field in BeanWrapperRowMapper would solve the it: https://github.com/adrian-pusty/spring-batch-extensions/commit/a727c46799539cf1d74a310335a5c2d813c95933#diff-0ac74f7f100e3eff66583af2aaf6350a51c3e650c198b699d1732da14fea0e71