## What changes were proposed in this pull request?
In both cases, the input `DataFrame` schema must contain only the information that's required for the matrix object, so a vector column in the case of `RowMatrix` and long and vector columns for `IndexedRowMatrix`.
## How was this patch tested?
Unit tests that verify:
- `RowMatrix` and `IndexedRowMatrix` can be created from `DataFrame`s
- If the schema does not match expectations, we throw an `IllegalArgumentException`
Please review https://spark.apache.org/contributing.html before opening a pull request.
Closes#24953 from henrydavidge/row-matrix-df.
Authored-by: Henry D <henrydavidge@gmail.com>
Signed-off-by: Sean Owen <sean.owen@databricks.com>
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