[SPARK-18692][BUILD][DOCS] Test Java 8 unidoc build on Jenkins

## What changes were proposed in this pull request?

This PR proposes to run Spark unidoc to test Javadoc 8 build as Javadoc 8 is easily re-breakable.

There are several problems with it:

- It introduces little extra bit of time to run the tests. In my case, it took 1.5 mins more (`Elapsed :[94.8746569157]`). How it was tested is described in "How was this patch tested?".

- > One problem that I noticed was that Unidoc appeared to be processing test sources: if we can find a way to exclude those from being processed in the first place then that might significantly speed things up.

  (see  joshrosen's [comment](https://issues.apache.org/jira/browse/SPARK-18692?focusedCommentId=15947627&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15947627))

To complete this automated build, It also suggests to fix existing Javadoc breaks / ones introduced by test codes as described above.

There fixes are similar instances that previously fixed. Please refer https://github.com/apache/spark/pull/15999 and https://github.com/apache/spark/pull/16013

Note that this only fixes **errors** not **warnings**. Please see my observation https://github.com/apache/spark/pull/17389#issuecomment-288438704 for spurious errors by warnings.

## How was this patch tested?

Manually via `jekyll build` for building tests. Also, tested via running `./dev/run-tests`.

This was tested via manually adding `time.time()` as below:

```diff
     profiles_and_goals = build_profiles + sbt_goals

     print("[info] Building Spark unidoc (w/Hive 1.2.1) using SBT with these arguments: ",
           " ".join(profiles_and_goals))

+    import time
+    st = time.time()
     exec_sbt(profiles_and_goals)
+    print("Elapsed :[%s]" % str(time.time() - st))
```

produces

```
...
========================================================================
Building Unidoc API Documentation
========================================================================
...
[info] Main Java API documentation successful.
...
Elapsed :[94.8746569157]
...

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #17477 from HyukjinKwon/SPARK-18692.

10 files changed, 23 insertions, 24 deletions

diff --git a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/Service.java b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/Service.java
index b95077cd62..0d0e3e4011 100644
--- a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/Service.java
+++ b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/Service.java
@@ -49,7 +49,7 @@ public interface Service {
    * The transition must be from {@link STATE#NOTINITED} to {@link STATE#INITED} unless the
    * operation failed and an exception was raised.
    *
-   * @param config
+   * @param conf
    *          the configuration of the service
    */
   void init(HiveConf conf);
diff --git a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/ServiceOperations.java b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/ServiceOperations.java
index a2c580d6ac..c3219aabfc 100644
--- a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/ServiceOperations.java
+++ b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/ServiceOperations.java
@@ -51,7 +51,7 @@ public final class ServiceOperations {
 
   /**
    * Initialize a service.
-   * <p/>
+   *
    * The service state is checked <i>before</i> the operation begins.
    * This process is <i>not</i> thread safe.
    * @param service a service that must be in the state
@@ -69,7 +69,7 @@ public final class ServiceOperations {
 
   /**
    * Start a service.
-   * <p/>
+   *
    * The service state is checked <i>before</i> the operation begins.
    * This process is <i>not</i> thread safe.
    * @param service a service that must be in the state
@@ -86,7 +86,7 @@ public final class ServiceOperations {
 
   /**
    * Initialize then start a service.
-   * <p/>
+   *
    * The service state is checked <i>before</i> the operation begins.
    * This process is <i>not</i> thread safe.
    * @param service a service that must be in the state
@@ -102,9 +102,9 @@ public final class ServiceOperations {
 
   /**
    * Stop a service.
-   * <p/>Do nothing if the service is null or not
-   * in a state in which it can be/needs to be stopped.
-   * <p/>
+   *
+   * Do nothing if the service is null or not in a state in which it can be/needs to be stopped.
+   *
    * The service state is checked <i>before</i> the operation begins.
    * This process is <i>not</i> thread safe.
    * @param service a service or null
diff --git a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/auth/HttpAuthUtils.java b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/auth/HttpAuthUtils.java
index 5021528299..f7375ee707 100644
--- a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/auth/HttpAuthUtils.java
+++ b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/auth/HttpAuthUtils.java
@@ -89,7 +89,7 @@ public final class HttpAuthUtils {
    * @param clientUserName Client User name.
    * @return An unsigned cookie token generated from input parameters.
    * The final cookie generated is of the following format :
-   * cu=<username>&rn=<randomNumber>&s=<cookieSignature>
+   * {@code cu=<username>&rn=<randomNumber>&s=<cookieSignature>}
    */
   public static String createCookieToken(String clientUserName) {
     StringBuffer sb = new StringBuffer();
diff --git a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/auth/PasswdAuthenticationProvider.java b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/auth/PasswdAuthenticationProvider.java
index e2a6de165a..1af1c1d06e 100644
--- a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/auth/PasswdAuthenticationProvider.java
+++ b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/auth/PasswdAuthenticationProvider.java
@@ -26,7 +26,7 @@ public interface PasswdAuthenticationProvider {
    * to authenticate users for their requests.
    * If a user is to be granted, return nothing/throw nothing.
    * When a user is to be disallowed, throw an appropriate {@link AuthenticationException}.
-   * <p/>
+   *
    * For an example implementation, see {@link LdapAuthenticationProviderImpl}.
    *
    * @param user     The username received over the connection request
diff --git a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/auth/TSetIpAddressProcessor.java b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/auth/TSetIpAddressProcessor.java
index 645e3e2bbd..9a61ad4994 100644
--- a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/auth/TSetIpAddressProcessor.java
+++ b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/auth/TSetIpAddressProcessor.java
@@ -31,12 +31,9 @@ import org.slf4j.LoggerFactory;
 
 /**
  * This class is responsible for setting the ipAddress for operations executed via HiveServer2.
- * <p>
- * <ul>
- * <li>IP address is only set for operations that calls listeners with hookContext</li>
- * <li>IP address is only set if the underlying transport mechanism is socket</li>
- * </ul>
- * </p>
+ *
+ * - IP address is only set for operations that calls listeners with hookContext
+ * - IP address is only set if the underlying transport mechanism is socket
  *
  * @see org.apache.hadoop.hive.ql.hooks.ExecuteWithHookContext
  */
diff --git a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/cli/CLIServiceUtils.java b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/cli/CLIServiceUtils.java
index 9d64b102e0..bf2380632f 100644
--- a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/cli/CLIServiceUtils.java
+++ b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/cli/CLIServiceUtils.java
@@ -38,7 +38,7 @@ public class CLIServiceUtils {
    * Convert a SQL search pattern into an equivalent Java Regex.
    *
    * @param pattern input which may contain '%' or '_' wildcard characters, or
-   * these characters escaped using {@link #getSearchStringEscape()}.
+   * these characters escaped using {@code getSearchStringEscape()}.
    * @return replace %/_ with regex search characters, also handle escaped
    * characters.
    */
diff --git a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/cli/operation/ClassicTableTypeMapping.java b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/cli/operation/ClassicTableTypeMapping.java
index 05a6bf9384..af36057bda 100644
--- a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/cli/operation/ClassicTableTypeMapping.java
+++ b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/cli/operation/ClassicTableTypeMapping.java
@@ -28,9 +28,9 @@ import org.apache.hadoop.hive.metastore.TableType;
 /**
  * ClassicTableTypeMapping.
  * Classic table type mapping :
- *  Managed Table ==> Table
- *  External Table ==> Table
- *  Virtual View ==> View
+ *  Managed Table to Table
+ *  External Table to Table
+ *  Virtual View to View
  */
 public class ClassicTableTypeMapping implements TableTypeMapping {
 
diff --git a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/cli/operation/TableTypeMapping.java b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/cli/operation/TableTypeMapping.java
index e392c459cf..e59d19ea6b 100644
--- a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/cli/operation/TableTypeMapping.java
+++ b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/cli/operation/TableTypeMapping.java
@@ -31,7 +31,7 @@ public interface TableTypeMapping {
 
   /**
    * Map hive's table type name to client's table type
-   * @param clientTypeName
+   * @param hiveTypeName
    * @return
    */
   String mapToClientType(String hiveTypeName);
diff --git a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/cli/session/SessionManager.java b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/cli/session/SessionManager.java
index de066dd406..c1b3892f52 100644
--- a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/cli/session/SessionManager.java
+++ b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/cli/session/SessionManager.java
@@ -224,7 +224,9 @@ public class SessionManager extends CompositeService {
    * The username passed to this method is the effective username.
    * If withImpersonation is true (==doAs true) we wrap all the calls in HiveSession
    * within a UGI.doAs, where UGI corresponds to the effective user.
-   * @see org.apache.hive.service.cli.thrift.ThriftCLIService#getUserName()
+   *
+   * Please see {@code org.apache.hive.service.cli.thrift.ThriftCLIService.getUserName()} for
+   * more details.
    *
    * @param protocol
    * @param username
diff --git a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/server/ThreadFactoryWithGarbageCleanup.java b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/server/ThreadFactoryWithGarbageCleanup.java
index fb8141a905..94f8126552 100644
--- a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/server/ThreadFactoryWithGarbageCleanup.java
+++ b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/server/ThreadFactoryWithGarbageCleanup.java
@@ -30,12 +30,12 @@ import org.apache.hadoop.hive.metastore.RawStore;
  * in custom cleanup code to be called before this thread is GC-ed.
  * Currently cleans up the following:
  * 1. ThreadLocal RawStore object:
- * In case of an embedded metastore, HiveServer2 threads (foreground & background)
+ * In case of an embedded metastore, HiveServer2 threads (foreground and background)
  * end up caching a ThreadLocal RawStore object. The ThreadLocal RawStore object has
- * an instance of PersistenceManagerFactory & PersistenceManager.
+ * an instance of PersistenceManagerFactory and PersistenceManager.
  * The PersistenceManagerFactory keeps a cache of PersistenceManager objects,
  * which are only removed when PersistenceManager#close method is called.
- * HiveServer2 uses ExecutorService for managing thread pools for foreground & background threads.
+ * HiveServer2 uses ExecutorService for managing thread pools for foreground and background threads.
  * ExecutorService unfortunately does not provide any hooks to be called,
  * when a thread from the pool is terminated.
  * As a solution, we're using this ThreadFactory to keep a cache of RawStore objects per thread.