Added double int long summary statistics
added join strings example
java 8 string joiner example added
Added empty sorted map
Added empty sorted set
added java 8 example encode string
added java 8 example encode
added java 8 example
added objects example
added java.util.function.predicate example
added optional examples
updated URL
Added stream filter and slice
added example on how to build a stream
added example using stream on how to find* methods