## What changes were proposed in this pull request?
Join on transformed dataset has attributes conflicts, which make query execution failure, for example:
```
val dataset = Seq(1, 2, 3).toDs
val mappedDs = dataset.map(_ + 1)
mappedDs.as("t1").joinWith(mappedDs.as("t2"), $"t1.value" === $"t2.value").show()
```
will throw exception:
```
org.apache.spark.sql.AnalysisException: cannot resolve '`t1.value`' given input columns: [value];
at org.apache.spark.sql.catalyst.analysis.package$AnalysisErrorAt.failAnalysis(package.scala:42)
at org.apache.spark.sql.catalyst.analysis.CheckAnalysis$$anonfun$checkAnalysis$1$$anonfun$apply$2.applyOrElse(CheckAnalysis.scala:62)
at org.apache.spark.sql.catalyst.analysis.CheckAnalysis$$anonfun$checkAnalysis$1$$anonfun$apply$2.applyOrElse(CheckAnalysis.scala:59)
at org.apache.spark.sql.catalyst.trees.TreeNode$$anonfun$transformUp$1.apply(TreeNode.scala:287)
at org.apache.spark.sql.catalyst.trees.TreeNode$$anonfun$transformUp$1.apply(TreeNode.scala:287)
```
## How was this patch tested?
Unit test.
Author: jerryshao <sshao@hortonworks.com>
Closes#13399 from jerryshao/SPARK-15620.
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