docs: explain default generation config in README.md

[JoeWang1127]

No description provided.

[blakeli0]

Can we add a sentence before this section mentioning something like "All the parameters are optional, but a generation_config.yaml is required"?

[JoeWang1127]

I added this to Prerequisites.

[sonarcloud]

Quality Gate passed for 'gapic-generator-java-root'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[sonarcloud]

Quality Gate passed for 'java_showcase_integration_tests'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[blakeli0]

IIRC, we would generate a versions.txt file if it does not exist. Can you confirm @diegomarquezp ?

[diegomarquezp]

No, it is not generated. The scripts will just fail if not found.

sdk-platform-java/hermetic_build/library_generation/utils/utilities.py

Lines 124 to 142 in 1080de4

	def prepare_repo(
	gen_config: GenerationConfig,
	library_config: List[LibraryConfig],
	repo_path: str,
	language: str = "java",
	) -> RepoConfig:
	"""
	Gather information of the generated repository.
	:param gen_config: a GenerationConfig object representing a parsed
	configuration yaml
	:param library_config: a LibraryConfig object contained inside config,
	passed here for convenience and to prevent all libraries to be processed
	:param repo_path: the path to which the generated repository goes
	:param language: programming language of the library
	:return: a RepoConfig object contained repository information
	:raise FileNotFoundError if there's no versions.txt in repo_path
	:raise ValueError if two libraries have the same library_name
	"""

[blakeli0]

I see, thanks for the quick response!

[JoeWang1127]

The file is required, per

sdk-platform-java/hermetic_build/library_generation/utils/utilities.py

Line 164 in 7d6d66a

raise FileNotFoundError(f"{versions_file} is not found.")

Though I think we can create an empty file if not exist since we didn't check the contents.

I'll create a follow-up issue.