Add optional field getters in builder (isSetXxx() and xxx())

[AndreasIgel]

Feature Request

Inspired by RecordBuilder's field getter pattern, where the builder exposes accessor methods to read back the current state of each field during construction.

Current State

The TrackedValue infrastructure already has .isSet() and .value() methods, but these are only used internally (in build(), collection add, etc.). There are no public getters on the builder to read field values from outside.

Proposed Feature

Add an optional annotation flag generateFieldGetters = true to @SimpleBuilder / @SimpleMinimalBuilder that generates two methods per field:

// Check if a field was explicitly set
public boolean isSetAccreditationName() {
 return this.accreditationName.isSet();
}

// Read the current value (null if unset)
public String accreditationName() {
 return this.accreditationName.value();
}

Use Cases

• Conditional logic during building: if (builder.accreditationName() == null) builder.accreditationName("UNKNOWN");
• Check if explicitly set: if (!builder.isSetAccreditationName()) { /* only set default if user didn't */ }
• Debugging: Inspect builder state mid-construction
• Validation: Read value, validate, optionally override before build

Why Optional?

Adding getters increases the builder's API surface. Users who want a minimal builder (like @SimpleMinimalBuilder) may not want these methods. Making it opt-in via a flag keeps the default behavior unchanged.

Implementation Notes

• Delegates to existing TrackedValue.isSet() and TrackedValue.value() — minimal implementation effort
• Should be a new generator or enhancer with a configurable priority
• Consider naming: isSetXxx() vs hasXxx() — isSet is consistent with TrackedValue terminology