[FSSDK-11874] Remove holdouts from master (#420)

* Rename ODP cache.go to lru_cache.go to match original naming convention

* Remove holdout functionality from master - prepare for clean CMAB v2.2.0 release

- Revert all holdout-related changes from PR #415
- Remove Holdout structs, methods, and processing logic from:
  * pkg/entities/experiment.go
  * pkg/config/datafileprojectconfig/entities/entities.go
  * pkg/config/datafileprojectconfig/config.go
  * pkg/config/datafileprojectconfig/config_test.go
  * pkg/config/datafileprojectconfig/mappers/experiment_test.go
- Holdout functionality preserved in disable-holdouts-feature-toggle branch
- Maintain clean CMAB-only release per reviewer requirements
- All tests pass, public API compatibility maintained

* Add missing Cache interface to pkg/odp for backward compatibility

- Add Cache interface to pkg/odp/lru_cache.go
- Maintains backward compatibility for existing code importing from pkg/odp
- Fixes breaking change where users could no longer use odp.Cache
- Per reviewer feedback to preserve old public interfaces

* Move cache interface back to pkg/odp/cache for backward compatibility

- Move pkg/odp/lru_cache.go to pkg/odp/cache/lru_cache.go
- Update package declaration from 'odp' to 'cache'
- Update imports to use alias 'pkgCache' to avoid naming conflicts
- Restores the original import path for users who import pkg/odp/cache
- Addresses reviewer feedback about restoring old cache path structure

* Fix gofmt formatting issue in cache file

Remove trailing whitespace from comment line to fix linter error.

Author: Mat001

pkg/config/datafileprojectconfig/config.go

@@ -21,7 +21,6 @@ import (
 	"errors"
 	"fmt"
 
-	datafileEntities "github.com/optimizely/go-sdk/v2/pkg/config/datafileprojectconfig/entities"
 	"github.com/optimizely/go-sdk/v2/pkg/config/datafileprojectconfig/mappers"
 	"github.com/optimizely/go-sdk/v2/pkg/entities"
 	"github.com/optimizely/go-sdk/v2/pkg/logging"
@@ -59,12 +58,8 @@ type DatafileProjectConfig struct {
 	sdkKey               string
 	environmentKey       string
 	region               string
-	flagVariationsMap    map[string][]entities.Variation
-	holdoutIDMap         map[string]entities.Holdout
-	globalHoldouts       []entities.Holdout
-	includedHoldouts     map[string][]entities.Holdout
-	excludedHoldouts     map[string][]entities.Holdout
-	flagHoldoutsMap      map[string][]entities.Holdout
+
+	flagVariationsMap map[string][]entities.Variation
 }
 
 // GetDatafile returns a string representation of the environment's datafile
@@ -271,56 +266,6 @@ func (c DatafileProjectConfig) GetGroupByID(groupID string) (entities.Group, err
 	return entities.Group{}, fmt.Errorf(`group with ID "%s" not found`, groupID)
 }
 
-// GetHoldoutsForFlag returns the holdouts that apply to a specific flag
-func (c *DatafileProjectConfig) GetHoldoutsForFlag(flagKey string) []entities.Holdout {
-	// Get flag ID from key
-	feature, exists := c.featureMap[flagKey]
-	if !exists {
-		return []entities.Holdout{}
-	}
-
-	flagID := feature.ID
-
-	// Check cache first
-	if cachedHoldouts, exists := c.flagHoldoutsMap[flagID]; exists {
-		return cachedHoldouts
-	}
-
-	holdouts := []entities.Holdout{}
-
-	// Add global holdouts that don't exclude this flag
-	for _, holdout := range c.globalHoldouts {
-		isExcluded := false
-		for _, excludedFlagID := range holdout.ExcludedFlags {
-			if excludedFlagID == flagID {
-				isExcluded = true
-				break
-			}
-		}
-		if !isExcluded {
-			holdouts = append(holdouts, holdout)
-		}
-	}
-
-	// Add holdouts that specifically include this flag
-	if includedHoldouts, exists := c.includedHoldouts[flagID]; exists {
-		holdouts = append(holdouts, includedHoldouts...)
-	}
-
-	// Cache the result
-	c.flagHoldoutsMap[flagID] = holdouts
-
-	return holdouts
-}
-
-// GetHoldout returns a holdout by its ID
-func (c DatafileProjectConfig) GetHoldout(holdoutID string) (entities.Holdout, error) {
-	if holdout, ok := c.holdoutIDMap[holdoutID]; ok {
-		return holdout, nil
-	}
-	return entities.Holdout{}, fmt.Errorf(`holdout with ID "%s" not found`, holdoutID)
-}
-
 // SendFlagDecisions determines whether impressions events are sent for ALL decision types
 func (c DatafileProjectConfig) SendFlagDecisions() bool {
 	return c.sendFlagDecisions
@@ -379,48 +324,6 @@ func NewDatafileProjectConfig(jsonDatafile []byte, logger logging.OptimizelyLogP
 	audienceMap, audienceSegmentList := mappers.MapAudiences(append(datafile.TypedAudiences, datafile.Audiences...))
 	flagVariationsMap := mappers.MapFlagVariations(featureMap)
 
-	// Process holdouts
-	holdoutIDMap := make(map[string]entities.Holdout)
-	globalHoldouts := []entities.Holdout{}
-	includedHoldouts := make(map[string][]entities.Holdout)
-	excludedHoldouts := make(map[string][]entities.Holdout)
-	flagHoldoutsMap := make(map[string][]entities.Holdout)
-
-	for _, datafileHoldout := range datafile.Holdouts {
-		// Only process running holdouts
-		if datafileHoldout.Status != datafileEntities.HoldoutStatusRunning {
-			continue
-		}
-
-		// Create runtime holdout entity
-		holdout := entities.Holdout{
-			ID:            datafileHoldout.ID,
-			Key:           datafileHoldout.Key,
-			Status:        entities.HoldoutStatus(datafileHoldout.Status),
-			IncludedFlags: datafileHoldout.IncludedFlags,
-			ExcludedFlags: datafileHoldout.ExcludedFlags,
-		}
-
-		// Add to ID map
-		holdoutIDMap[holdout.ID] = holdout
-
-		// Categorize holdouts based on flag targeting
-		if len(datafileHoldout.IncludedFlags) == 0 {
-			// This is a global holdout (applies to all flags unless excluded)
-			globalHoldouts = append(globalHoldouts, holdout)
-
-			// Add to excluded flags map
-			for _, flagID := range datafileHoldout.ExcludedFlags {
-				excludedHoldouts[flagID] = append(excludedHoldouts[flagID], holdout)
-			}
-		} else {
-			// This holdout specifically includes certain flags
-			for _, flagID := range datafileHoldout.IncludedFlags {
-				includedHoldouts[flagID] = append(includedHoldouts[flagID], holdout)
-			}
-		}
-	}
-
 	attributeKeyMap := make(map[string]entities.Attribute)
 	attributeIDToKeyMap := make(map[string]string)
 
@@ -462,11 +365,6 @@ func NewDatafileProjectConfig(jsonDatafile []byte, logger logging.OptimizelyLogP
 		attributeKeyMap:      attributeKeyMap,
 		attributeIDToKeyMap:  attributeIDToKeyMap,
 		region:               region,
-		holdoutIDMap:         holdoutIDMap,
-		globalHoldouts:       globalHoldouts,
-		includedHoldouts:     includedHoldouts,
-		excludedHoldouts:     excludedHoldouts,
-		flagHoldoutsMap:      flagHoldoutsMap,
 	}
 
 	logger.Info("Datafile is valid.")