Minor Description
Similar to spark-29291, just to track Spark 3.1.0.
There are two similar compilation warnings about procedure-like declaration in Scala 2.13.3:
[WARNING] [Warn] /spark/core/src/main/scala/org/apache/spark/HeartbeatReceiver.scala:70: procedure syntax is deprecated for constructors: add `=`, as in method definition [WARNING] [Warn] /spark/core/src/main/scala/org/apache/spark/storage/BlockManagerDecommissioner.scala:211: procedure syntax is deprecated: instead, add `: Unit =` to explicitly declare `run`'s return type
For constructors method definition should be `this(...) = { }` not `this(...) { }`, for without
`return type` methods definition should be `def methodName(...): Unit = {}` not `def methodName(...) {}`
