Make snakeyaml-engine and jackson-databind optional at runtime

[zeitlinger]

Summary

This PR does two things:

1. Split YAML parsing out of DeclarativeConfiguration

DeclarativeConfiguration is split into two classes to make YAML dependencies optional at runtime:

• DeclarativeConfiguration — create(model) methods only. No dependency on snakeyaml-engine or jackson-databind at runtime.
• DeclarativeConfigurationParser — all YAML parsing: MAPPER static block, parse(), loadYaml(), parseAndCreate(), toConfigProperties(), env-var substitution.

The MAPPER field in the original class is a static final with a static initializer. Loading the class to call create(model) triggered that static block, failing with NoClassDefFoundError if jackson-databind was absent. Moving the static block to DeclarativeConfigurationParser breaks the link — the JVM only loads it when parser methods are actually called.

2. Move all declarative config (fileconfig) from incubator into autoconfigure

All ~45 fileconfig source files are moved from sdk-extensions/incubator to sdk-extensions/autoconfigure. This is the direction suggested in #8265 — the YAML dep concern is resolved by the class split above.

A new sdk-extensions/autoconfigure-config convenience module bundles autoconfigure + snakeyaml-engine + jackson-databind for users who want everything in one dependency (Spring Boot starter style).

Dependency graph

graph TD
    config["autoconfigure-config\n(convenience bundle)"]
    autoconfigure["autoconfigure\n(fileconfig included)"]
    incubator["incubator\n(ViewConfig, SPI extensions)"]
    api-incubator["api:incubator"]
    snakeyaml["snakeyaml-engine"]
    jackson["jackson-databind"]
    jackson-ann["jackson-annotations"]

    config -->|api| autoconfigure
    config -->|runtimeOnly| snakeyaml
    config -->|runtimeOnly| jackson

    autoconfigure -->|api| jackson-ann
    autoconfigure -.->|"compileOnly (YAML parsing)"| snakeyaml
    autoconfigure -.->|"compileOnly (YAML parsing)"| jackson
    autoconfigure -.->|"compileOnly (fileconfig)"| api-incubator
    autoconfigure -.->|"compileOnly (optional SPI)"| incubator

    incubator -->|api| api-incubator

Loading

Dashed arrows = compileOnly / optional at runtime. YAML file config requires snakeyaml + jackson + api:incubator at runtime; autoconfigure-config provides all three.

What changes for users

Use case	Before	After
AutoConfiguredOpenTelemetrySdk (env/props only)	autoconfigure	autoconfigure (unchanged)
YAML file config (otel.config.file)	autoconfigure + incubator + snakeyaml + jackson	autoconfigure-config
Programmatic DeclarativeConfiguration.create(model)	incubator + snakeyaml + jackson (YAML deps leaked)	autoconfigure only
SPI-based declarative config	autoconfigure + incubator + api:incubator	same

Related to / supersedes the direction in #8265.

[codecov]

Codecov Report

❌ Patch coverage is 89.47368% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.29%. Comparing base (1e0ddc6) to head (d6ba0ff).

Files with missing lines	Patch %	Lines
...incubator/fileconfig/DeclarativeConfiguration.java	86.48%	4 Missing and 1 partial ⚠️
...nfigure/AutoConfiguredOpenTelemetrySdkBuilder.java	87.50%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #8270      +/-   ##
============================================
- Coverage     90.29%   90.29%   -0.01%     
- Complexity     7656     7657       +1     
============================================
  Files           844      845       +1     
  Lines         23071    23081      +10     
  Branches       2311     2311              
============================================
+ Hits          20832    20841       +9     
  Misses         1521     1521              
- Partials        718      719       +1     

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