PARQUET-1460: Fix javadoc errors and include javadoc checking in Travis checks

.travis.yml

@@ -35,4 +35,4 @@ env:
   - HADOOP_PROFILE=default TEST_CODECS=gzip,snappy
 
 install: mvn install --batch-mode -DskipTests=true -Dmaven.javadoc.skip=true -Dsource.skip=true | pv -fbi 60 > mvn_install.log || (cat mvn_install.log && false)
-script: mvn verify -P $HADOOP_PROFILE
+script: mvn verify javadoc:javadoc -P $HADOOP_PROFILE

parquet-benchmarks/src/main/java/org/apache/parquet/benchmarks/FilteringBenchmarks.java

@@ -79,7 +79,7 @@
  * <a href="https://jmh.morethan.io">https://jmh.morethan.io</a>.
  *
  * <pre>
- * mvn clean package && java -jar target/parquet-benchmarks.jar org.apache.parquet.benchmarks.FilteringBenchmarks -rf json
+ * mvn clean package &amp;&amp; java -jar target/parquet-benchmarks.jar org.apache.parquet.benchmarks.FilteringBenchmarks -rf json
  * </pre>
  */
 @BenchmarkMode(SingleShotTime)

parquet-hadoop/src/main/java/org/apache/parquet/hadoop/ParquetFileReader.java

@@ -864,12 +864,12 @@ public PageReadStore readNextRowGroup() throws IOException {
   /**
    * Reads all the columns requested from the row group at the current file position. It may skip specific pages based
    * on the column indexes according to the actual filter. As the rows are not aligned among the pages of the different
-   * columns row synchronization might be required.
+   * columns row synchronization might be required. See the documentation of the class SynchronizingColumnReader for
+   * details.
    *
    * @return the PageReadStore which can provide PageReaders for each column
    * @throws IOException
    *           if any I/O error occurs while reading
-   * @see {@link PageReadStore#isInPageFilteringMode()}
    */
   public PageReadStore readNextFilteredRowGroup() throws IOException {
     if (currentBlock == blocks.size()) {