Fix DefaultHlsExtractorFactory javadoc

Issue:#2748

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=174854541

library/hls/src/main/java/com/google/android/exoplayer2/source/hls/DefaultHlsExtractorFactory.java

@@ -34,8 +34,6 @@ import java.util.List;
 
 
 /**
 /**
  * Default {@link HlsExtractorFactory} implementation.
  * Default {@link HlsExtractorFactory} implementation.
- *
- * <p>This class can be extended to override {@link TsExtractor} instantiation.</p>
  */
  */
 public final class DefaultHlsExtractorFactory implements HlsExtractorFactory {
 public final class DefaultHlsExtractorFactory implements HlsExtractorFactory {