A readable source of bytes, such as a file. Unlike an InputStream, a ByteSource is not an open, stateful stream for input that can be read and closed. Instead, it is an immutable supplier of InputStream instances.

ByteSource provides two kinds of methods:

• Methods that return a stream: These methods should return a new, independent instance each time they are called. The caller is responsible for ensuring that the returned stream is closed.
• Convenience methods: These are implementations of common operations that are typically implemented by opening a stream using one of the methods in the first category, doing something and finally closing the stream that was opened.

Note: In general, ByteSource is intended to be used for "file-like" sources that provide streams that are:

• Finite: Many operations, such as size() and read(), will either block indefinitely or fail if the source creates an infinite stream.
• Non-destructive: A destructive stream will consume or otherwise alter the bytes of the source as they are read from it. A source that provides such streams will not be reusable, and operations that read from the stream (including size(), in some implementations) will prevent further operations from completing as expected.