getColumn(String fullName) this method is called when column name is specified as TABLE_NAME.COLUMN_NAME, this
method first column it finds from source or target tables.
this method is called when column name is specified as TABLE_NAME.COLUMN_NAME, this
method first column it finds from source or target tables. For accurate result user
should type fully qualified column name.
This method will return a column when user types a fully qualified column name. for
oracle fully qualified name is SCHEMA_NAME.TABLE.NAME.COLUMN.NAME for sql server it
is CATALOG_NAME.SCHEMA_NAME.TABLE.NAME.COLUMN.NAME