import java.util.List; import java.util.Set; import java.util.stream.Collectors; import java.util.stream.Stream; class IDEA129251 { void simplified(final Stream<String> pStream, final Stream<String> pStream1, final Stream<String> pStream2){ pStream.flatMap(x -> Stream.concat(pStream1, pStream2.map(String::toUpperCase))); } private final Set<String> m_allSubtablesColumns; private final List<SubtableDescription> m_subtablesDescription = null; { m_allSubtablesColumns = m_subtablesDescription.stream(). flatMap(desc -> Stream.concat(desc.getKeyColumns().stream().map(String::toUpperCase), desc.getValueColumns().stream().map(String::toUpperCase))). collect(Collectors.toSet()); } abstract class SubtableDescription { abstract List<String> getKeyColumns(); abstract List<String> getValueColumns(); } }