## What changes were proposed in this pull request?
Avro schema allows recursive reference, e.g. the schema for linked-list in https://avro.apache.org/docs/1.8.2/spec.html#schema_record
```
{
"type": "record",
"name": "LongList",
"aliases": ["LinkedLongs"], // old name for this
"fields" : [
{"name": "value", "type": "long"}, // each element has a long
{"name": "next", "type": ["null", "LongList"]} // optional next element
]
}
```
In current Spark SQL, it is impossible to convert the schema as `StructType` . Run `SchemaConverters.toSqlType(avroSchema)` and we will get stack overflow exception.
We should detect the recursive reference and throw exception for it.
## How was this patch tested?
New unit test case.
Closes#22709 from gengliangwang/avroRecursiveRef.
Authored-by: Gengliang Wang <gengliang.wang@databricks.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
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