<p>{@link ContentProvider} provides a source of request content.</p> <p>Implementations should return an {@link Iterator} over the request content. If the request content comes from a source that needs to be closed (for example, an {@link java.io.InputStream}), then the iterator implementation class must implement {@link Closeable} and will be closed when the request is completed (either successfully or failed).</p> <p>{@link ContentProvider} provides a {@link #getLength() length} of the content it represents. If the length is positive, it typically overrides any {@code Content-Length} header set by applications; if the length is negative, it typically removes any {@code Content-Length} header set by applications, resulting in chunked content (i.e. {@code Transfer-Encoding: chunked}) being sent to the server.</p>