Consider making JibContainerBuilder interface more fluent.

Continuing from #881…

Considering that we are modeling JibContainerBuilder’s interface off of the Stream API, and that JibContainerBuilder begins with Jib.from, we should probably make the rest of the API more fluent as well.

addLayer(List<Path>, String) -> layer(List<Path>, String) addLayer(LayerConfiguration) -> layer(LayerConfiguration) setLayers(List<LayerConfiguration>) -> layer(List<LayerConfiguration>) setEntrypoint(List<String>/String...) -> entrypoint(List<String>/String...) setProgramArguments(List<String>/String...) -> programArguments(List<String>/String...) setEnvironment(Map<String, String>) -> environment(Map<String, String>) setEnvironmentVariable(String, String) -> environmentVariable(String, String) setExposedPorts(List<Port>/Port...) -> expose(List<Port>/Port...) addExposedPort(Port) -> expose(Port) setLabels(Map<String, String>) -> label(Map<String, String>) addLabel(String, String) -> label(String, String)

Also, currently, the collection setters (like setExposedPorts) replace previously-set ports. If converting to use this more fluent API, these collection setters should append, not replace. We could add methods like exposeOnly(Map) that behaves like the original setters.

[briandealwis]

We could provide exposeOnly(Map<>) variants that take a Map?

[coollog]

Closing and sticking with current design since it is clearer in the functions’ intentions, especially for methods like addExposedPort vs setExposedPort (expose vs exposeOnly is less clear and still involves extra Only portion).