IndexReader reader2 = w2.getReader();
w2.close();
TermsFilter tf = new TermsFilter(new Term(fieldName, "content1"));
MultiReader multi = new MultiReader(reader1, reader2);
for (AtomicReaderContext context : multi.leaves()) {
DocIdSet docIdSet = tf.getDocIdSet(context, context.reader().getLiveDocs());
if (context.reader().docFreq(new Term(fieldName, "content1")) == 0) {
assertNull(docIdSet);
} else {
FixedBitSet bits = (FixedBitSet) docIdSet;