issue-1384: Fluent API - Add JavaDoc to core workflow builders [TIER 1]

[domhanak]

Many thanks for submitting your Pull Request ❤️!

What this PR does / why we need it:
This PR is initial draft of the JavaDoc implementation proposed in #1384

Special notes for reviewers:

This is a result of analysis using IBM Bob, I am creating this draft PR to gather feedback and also have better view on the result ( I prefer reviewing here in GH )

Additional information (if needed):

Bob analyzed we have 4 TIERS ( we should prioritize - 1 highest, 4 lowest )
Each tier is split into smaller unit and this is a result of Bob solving first part of TIER 1
TIER 1 JavaDoc improvements - Unit 1.1: Fluent API Core Workflow Builders <- This PR

Pending, will continue if we deem the result good:
TIER 1 JavaDoc improvements - Unit 1.2: Fluent API Call & Communication Tasks
TIER 1 JavaDoc improvements - Unit 1.3: Fluent API Event Handling
TIER 1 JavaDoc improvements - Unit 1.4: Fluent API Error Handling & Control Flow
TIER 1 JavaDoc improvements - Unit 1.5: Core Runtime Application & Definition
TIER 1 JavaDoc improvements - Unit 1.6: Core Runtime Instance & Execution
TIER 1 JavaDoc improvements - Unit 1.7: Annotations

Guidelines applied when generating the docs:

✅ Class-level JavaDoc with:

Brief one-line descriptions
Detailed explanations of purpose and usage
Complete usage examples (2-4 per class)
Links to related classes using @see tags
Thread-safety notes
@since tags (1.0.0)
✅ Method-level JavaDoc with:

Clear descriptions using present tense
@param tags for all parameters
@return tags for builder methods
Usage examples for complex methods
@see references to related methods
✅ Builder Pattern Documentation:

Method chaining explained
Builder lifecycle clarified
Complete builder usage examples
Immutability/mutability notes
✅ Style Guidelines:

Present tense throughout
Concise but complete descriptions
Code examples in {@code} and <pre>{@code}</pre> blocks
Proper HTML tags in JavaDoc
Consistent formatting across all files
No code logic changes - only JavaDoc additions```