apache/lucene/index/IndexWriter.html?is-external=true#SOURCE_ADDINDEXES_READERS" title="class or interface in org.apache.lucene.index">SOURCE_ADDINDEXES_READERS</a>, <a href="http://lucene.apache.org/core/5_1_0/core/org/apache/lucene/index/IndexWriter.html?is-external=true#SOURCE_FLUSH" title="class or interface in org.apache.lucene.index">SOURCE_FLUSH</a>, <a href="http://lucene.apache.org/core/5_1_0/core/org/apache/lucene/index/IndexWriter.html?is-external=true#SOURCE_MERGE" title="class or interface in o