[SPARK-3359][BUILD][DOCS] More changes to resolve javadoc 8 errors that will help unidoc/genjavadoc compatibility

## What changes were proposed in this pull request?

This PR only tries to fix things that looks pretty straightforward and were fixed in other previous PRs before.

This PR roughly fixes several things as below:

- Fix unrecognisable class and method links in javadoc by changing it from `[[..]]` to `` `...` ``

  ```
  [error] .../spark/sql/core/target/java/org/apache/spark/sql/streaming/DataStreamReader.java:226: error: reference not found
  [error]    * Loads text files and returns a {link DataFrame} whose schema starts with a string column named
  ```

- Fix an exception annotation and remove code backticks in `throws` annotation

  Currently, sbt unidoc with Java 8 complains as below:

  ```
  [error] .../java/org/apache/spark/sql/streaming/StreamingQuery.java:72: error: unexpected text
  [error]    * throws StreamingQueryException, if <code>this</code> query has terminated with an exception.
  ```

  `throws` should specify the correct class name from `StreamingQueryException,` to `StreamingQueryException` without backticks. (see [JDK-8007644](https://bugs.openjdk.java.net/browse/JDK-8007644)).

- Fix `[[http..]]` to `<a href="http..."></a>`.

  ```diff
  -   * [[https://blogs.oracle.com/java-platform-group/entry/diagnosing_tls_ssl_and_https Oracle
  -   * blog page]].
  +   * <a href="https://blogs.oracle.com/java-platform-group/entry/diagnosing_tls_ssl_and_https">
  +   * Oracle blog page</a>.
  ```

   `[[http...]]` link markdown in scaladoc is unrecognisable in javadoc.

- It seems class can't have `return` annotation. So, two cases of this were removed.

  ```
  [error] .../java/org/apache/spark/mllib/regression/IsotonicRegression.java:27: error: invalid use of return
  [error]    * return New instance of IsotonicRegression.
  ```

- Fix < to `&lt;` and > to `&gt;` according to HTML rules.

- Fix `</p>` complaint

- Exclude unrecognisable in javadoc, `constructor`, `todo` and `groupname`.

## How was this patch tested?

Manually tested by `jekyll build` with Java 7 and 8

```
java version "1.7.0_80"
Java(TM) SE Runtime Environment (build 1.7.0_80-b15)
Java HotSpot(TM) 64-Bit Server VM (build 24.80-b11, mixed mode)
```

```
java version "1.8.0_45"
Java(TM) SE Runtime Environment (build 1.8.0_45-b14)
Java HotSpot(TM) 64-Bit Server VM (build 25.45-b02, mixed mode)
```

Note: this does not yet make sbt unidoc suceed with Java 8 yet but it reduces the number of errors with Java 8.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #15999 from HyukjinKwon/SPARK-3359-errors.

6 files changed, 9 insertions, 8 deletions

diff --git a/graphx/src/main/scala/org/apache/spark/graphx/Graph.scala b/graphx/src/main/scala/org/apache/spark/graphx/Graph.scala
index 922ec7955f..c55a5885ba 100644
--- a/graphx/src/main/scala/org/apache/spark/graphx/Graph.scala
+++ b/graphx/src/main/scala/org/apache/spark/graphx/Graph.scala
@@ -54,8 +54,8 @@ abstract class Graph[VD: ClassTag, ED: ClassTag] protected () extends Serializab
    *
    * @return an RDD containing the edges in this graph
    *
-   * @see [[Edge]] for the edge type.
-   * @see [[Graph#triplets]] to get an RDD which contains all the edges
+   * @see `Edge` for the edge type.
+   * @see `Graph#triplets` to get an RDD which contains all the edges
    * along with their vertex data.
    *
    */
diff --git a/graphx/src/main/scala/org/apache/spark/graphx/GraphLoader.scala b/graphx/src/main/scala/org/apache/spark/graphx/GraphLoader.scala
index f678e5f123..add21f41ea 100644
--- a/graphx/src/main/scala/org/apache/spark/graphx/GraphLoader.scala
+++ b/graphx/src/main/scala/org/apache/spark/graphx/GraphLoader.scala
@@ -32,7 +32,7 @@ object GraphLoader extends Logging {
    * id and a target id. Skips lines that begin with `#`.
    *
    * If desired the edges can be automatically oriented in the positive
-   * direction (source Id < target Id) by setting `canonicalOrientation` to
+   * direction (source Id &lt; target Id) by setting `canonicalOrientation` to
    * true.
    *
    * @example Loads a file in the following format:
diff --git a/graphx/src/main/scala/org/apache/spark/graphx/impl/EdgeRDDImpl.scala b/graphx/src/main/scala/org/apache/spark/graphx/impl/EdgeRDDImpl.scala
index 98e082cc44..faa985594e 100644
--- a/graphx/src/main/scala/org/apache/spark/graphx/impl/EdgeRDDImpl.scala
+++ b/graphx/src/main/scala/org/apache/spark/graphx/impl/EdgeRDDImpl.scala
@@ -41,7 +41,7 @@ class EdgeRDDImpl[ED: ClassTag, VD: ClassTag] private[graphx] (
 
   /**
    * If `partitionsRDD` already has a partitioner, use it. Otherwise assume that the
-   * [[PartitionID]]s in `partitionsRDD` correspond to the actual partitions and create a new
+   * `PartitionID`s in `partitionsRDD` correspond to the actual partitions and create a new
    * partitioner that allows co-partitioning with `partitionsRDD`.
    */
   override val partitioner =
diff --git a/graphx/src/main/scala/org/apache/spark/graphx/lib/PageRank.scala b/graphx/src/main/scala/org/apache/spark/graphx/lib/PageRank.scala
index f926984aa6..feb3f47667 100644
--- a/graphx/src/main/scala/org/apache/spark/graphx/lib/PageRank.scala
+++ b/graphx/src/main/scala/org/apache/spark/graphx/lib/PageRank.scala
@@ -28,7 +28,7 @@ import org.apache.spark.ml.linalg.{Vector, Vectors}
 /**
  * PageRank algorithm implementation. There are two implementations of PageRank implemented.
  *
- * The first implementation uses the standalone [[Graph]] interface and runs PageRank
+ * The first implementation uses the standalone `Graph` interface and runs PageRank
  * for a fixed number of iterations:
  * {{{
  * var PR = Array.fill(n)( 1.0 )
@@ -41,7 +41,7 @@ import org.apache.spark.ml.linalg.{Vector, Vectors}
  * }
  * }}}
  *
- * The second implementation uses the [[Pregel]] interface and runs PageRank until
+ * The second implementation uses the `Pregel` interface and runs PageRank until
  * convergence:
  *
  * {{{
diff --git a/graphx/src/main/scala/org/apache/spark/graphx/lib/SVDPlusPlus.scala b/graphx/src/main/scala/org/apache/spark/graphx/lib/SVDPlusPlus.scala
index bb2ffab0f6..59fdd855e6 100644
--- a/graphx/src/main/scala/org/apache/spark/graphx/lib/SVDPlusPlus.scala
+++ b/graphx/src/main/scala/org/apache/spark/graphx/lib/SVDPlusPlus.scala
@@ -42,7 +42,8 @@ object SVDPlusPlus {
   /**
    * Implement SVD++ based on "Factorization Meets the Neighborhood:
    * a Multifaceted Collaborative Filtering Model",
-   * available at [[http://public.research.att.com/~volinsky/netflix/kdd08koren.pdf]].
+   * available at <a href="http://public.research.att.com/~volinsky/netflix/kdd08koren.pdf">
+   * here</a>.
    *
    * The prediction rule is rui = u + bu + bi + qi*(pu + |N(u)|^^-0.5^^*sum(y)),
    * see the details on page 6.
diff --git a/graphx/src/main/scala/org/apache/spark/graphx/lib/TriangleCount.scala b/graphx/src/main/scala/org/apache/spark/graphx/lib/TriangleCount.scala
index 34e9e22c3a..21b22968a1 100644
--- a/graphx/src/main/scala/org/apache/spark/graphx/lib/TriangleCount.scala
+++ b/graphx/src/main/scala/org/apache/spark/graphx/lib/TriangleCount.scala
@@ -36,7 +36,7 @@ import org.apache.spark.graphx._
  * self cycles and canonicalizes the graph to ensure that the following conditions hold:
  * <ul>
  * <li> There are no self edges</li>
- * <li> All edges are oriented src > dst</li>
+ * <li> All edges are oriented src &gt; dst</li>
  * <li> There are no duplicate edges</li>
  * </ul>
  * However, the canonicalization procedure is costly as it requires repartitioning the graph.