jonatan-ivanov / otel-spec-gh-464

Example and demo for https://github.com/open-telemetry/opentelemetry-specification/issues/464

Example and demo for open-telemetry/opentelemetry-specification#464

A few things to notice:

• The Meter class is just a dummy one, just to have something similar to the OTel Metrics Specs
• There are no Attibutes used
• The reporting is just printing to stdout, see: SimpleTimer
• Most of the components are from Micrometer see original code, comments and license and authors there: https://github.com/micrometer-metrics/micrometer/
• Clock is important, it guides and helps testing, see: MockClock
• Timer is also important it guides (see: Timer.Sample) the user to record duration, see: TimerDemo (There are other arrangements to do this, this is just an example)