Major Description
Currently, there are two supported methods to perform a join: join condition and one column name.
The documentation specifies that the join function can accept a list of conditions or a list of column names but neither are currently supported. This is discussed in issue SPARK-7197 as well.
Functionality should match the documentation which currently contains an example in /spark/python/pyspark/sql/dataframe.py line 560:
>>> df.join(df4, ['name', 'age']).select(df.name, df.age).collect()
[Row(name=u'Bob', age=5)]
"""