Fix Java example in Streaming Programming Guide

"val conf" was used instead of "SparkConf conf" in Java snippet.

Author: Santiago M. Mola <santi@mola.io>

Closes #2472 from smola/patch-1 and squashes the following commits:

5bfeb9b [Santiago M. Mola] Fix Java example in Streaming Programming Guide
[PySpark] remove unnecessary use of numSlices from pyspark tests

Author: Matthew Farrellee <matt@redhat.com>

Closes #2467 from mattf/master-pyspark-remove-numslices-from-tests and squashes the following commits:

c49a87b [Matthew Farrellee] [PySpark] remove unnecessary use of numSlices from pyspark tests
SPARK-3574. Shuffle finish time always reported as -1

The included test waits 100 ms after job completion for task completion events to come in so it can verify they have reasonable finish times.  Does anyone know a better way to wait on listener events that are expected to come in?

Author: Sandy Ryza <sandy@cloudera.com>

Closes #2440 from sryza/sandy-spark-3574 and squashes the following commits:

c81439b [Sandy Ryza] Fix test failure
b340956 [Sandy Ryza] SPARK-3574. Remove shuffleFinishTime metric
[SPARK-3609][SQL] Adds sizeInBytes statistics for Limit operator when all output attributes are of native data types

This helps to replace shuffled hash joins with broadcast hash joins in some cases.

Author: Cheng Lian <lian.cs.zju@gmail.com>

Closes #2468 from liancheng/more-stats and squashes the following commits:

32687dc [Cheng Lian] Moved the test case to PlannerSuite
5595a91 [Cheng Lian] Removes debugging code
73faf69 [Cheng Lian] Test case for auto choosing broadcast hash join
f30fe1d [Cheng Lian] Adds sizeInBytes estimation for Limit when all output types are native types
[SPARK-3414][SQL] Replace LowerCaseSchema with Resolver

**This PR introduces a subtle change in semantics for HiveContext when using the results in Python or Scala.  Specifically, while resolution remains case insensitive, it is now case preserving.**

_This PR is a follow up to #2293 (and to a lesser extent #2262 #2334)._

In #2293 the catalog was changed to store analyzed logical plans instead of unresolved ones.  While this change fixed the reported bug (which was caused by yet another instance of us forgetting to put in a `LowerCaseSchema` operator) it had the consequence of breaking assumptions made by `MultiInstanceRelation`.  Specifically, we can't replace swap out leaf operators in a tree without rewriting changed expression ids (which happens when you self join the same RDD that has been registered as a temp table).

In this PR, I instead remove the need to insert `LowerCaseSchema` operators at all, by moving the concern of matching up identifiers completely into analysis.  Doing so allows the test cases from both #2293 and #2262 to pass at the same time (and likely fixes a slew of other "unknown unknown" bugs).

While it is rolled back in this PR, storing the analyzed plan might actually be a good idea.  For instance, it is kind of confusing if you register a temporary table, change the case sensitivity of resolution and now you can't query that table anymore.  This can be addressed in a follow up PR.

Follow-ups:
 - Configurable case sensitivity
 - Consider storing analyzed plans for temp tables

Author: Michael Armbrust <michael@databricks.com>

Closes #2382 from marmbrus/lowercase and squashes the following commits:

c21171e [Michael Armbrust] Ensure the resolver is used for field lookups and ensure that case insensitive resolution is still case preserving.
d4320f1 [Michael Armbrust] Merge remote-tracking branch 'origin/master' into lowercase
2de881e [Michael Armbrust] Address comments.
219805a [Michael Armbrust] style
5b93711 [Michael Armbrust] Replace LowerCaseSchema with Resolver.
[SPARK-3599]Avoid loading properties file frequently

https://issues.apache.org/jira/browse/SPARK-3599

Author: WangTao <barneystinson@aliyun.com>
Author: WangTaoTheTonic <barneystinson@aliyun.com>

Closes #2454 from WangTaoTheTonic/avoidLoadingFrequently and squashes the following commits:

3681182 [WangTao] do not use clone
7dca036 [WangTao] use lazy val instead
2a79f26 [WangTaoTheTonic] Avoid loaing properties file frequently
MAINTENANCE: Automated closing of pull requests.

This commit exists to close the following pull requests on Github:

Closes #1328 (close requested by 'pwendell')
Closes #2314 (close requested by 'pwendell')
Closes #997 (close requested by 'pwendell')
Closes #550 (close requested by 'pwendell')
Closes #1506 (close requested by 'pwendell')
Closes #2423 (close requested by 'mengxr')
Closes #554 (close requested by 'joshrosen')
In some cases, the RDD.checkpoint does not work