guava/src/com/google/common/io/CharSink.java
@Beta
  public void writeLines(Stream<? extends CharSequence> lines) throws IOException {
    writeLines(lines, System.getProperty("line.separator"));
  }
@Beta
  public void writeLines(Stream<? extends CharSequence> lines) throws IOException {
    writeLines(lines, System.getProperty("line.separator"));
  }
@ Beta public void writeLines ( Stream < ? extends CharSequence > lines ) throws IOException { writeLines ( lines , System . getProperty ( "line.separator" ) ) ; }
Writes the given lines of text to this sink with each line (including the last) terminated with
the operating system's default line separator. This method is equivalent to {@code
writeLines(lines, System.getProperty("line.separator"))}.

@throws IOException if an I/O error occurs while writing to this sink
@since 22.0
Writes the given lines of text to this sink with each line ( including the last ) terminated with the operating system s default line separator . This method is equivalent to { @code writeLines ( lines System . getProperty ( line . separator )) } .