You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: path_cache_config.go
    path of file: ./repos/vault/builtin/logical/transit
    
    the code of the file until where you have to start completion: // Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: BUSL-1.1

package transit

import (
	"context"
	"errors"

	"github.com/hashicorp/vault/sdk/framework"
	"github.com/hashicorp/vault/sdk/logical"
)

func (b *backend) pathCacheConfig() *framework.Path {
	return &framework.Path{
		Pattern: "cache-config",

		DisplayAttrs: &framework.DisplayAttributes{
			OperationPrefix: operationPrefixTransit,
		},

		Fields: map[string]*framework.FieldSchema{
			"size": {
				Type:        framework.TypeInt,
				Required:    false,
				Default:     0,
				Description: `Size of cache, use 0 for an unlimited cache size, defaults to 0`,
			},
		},

		Operations: map
    
func (b *backend) pathCacheConfigRead(ctx context.Context, req *logical.Request, d *framework.FieldData) (*logical.Response, error) {
	// error if no cache is configured
	if !b.lm.GetUseCache() {
		return nil, errors.New(
			"caching is disabled for this transit mount",
		)
	}

	// Compare current and stored cache sizes. If they are different warn the user.
	currentCacheSize := b.lm.GetCacheSize()
	storedCacheSize, err := GetCacheSizeFromStorage(ctx, req.Storage)
	if err != nil {
		return nil, err
	}

	if currentCacheSize != storedCacheSize {
		err = b.lm.InitCache(storedCacheSize)
		if err != nil {
			return nil, err
		}
	}

	resp := &logical.Response{
		Data: map[string]interface{}{
			"size": storedCacheSize,
		},
	}

	return resp, nil
}