Container image build args can be overridden following their order of precedence

[rohanKanojia]

Component

JKube Kit

Description

Originally discussed in #2994 (comment)

Currently, JKube tries to discover Docker Build Args from the following sources:

• Build Args specified directly in ImageConfiguration
• Build Args specified via System Properties
• Build Args specified via Project Properties
• Build Args specified via Plugin configuration
• Docker Proxy Build Args detected from ~/.docker/config.json

At the moment BuildArgResolverUtil (introduced in #2994) throws an exception if the same keys are provided from different sources (mentioned above).

User's might want to override some of these build args on a single execution (for example while performing a single build from the command line).
To be able to allow for this, the behavior needs to be changed so that instead of throwing an exception in case of key collision, a warning is logged.

The proper order of precedence should be documented (and tested) too.

Acceptance Criteria

• A warning is logged in case of same keys provided via different methods.
• Precedence is documented in project documentation.

[rohanKanojia]

@manusa : We still need to change logic to allow overriding of build args. Current behavior in #2994 is to throw exception on if build args with same keys are provided.