<?php

namespace EGALL\Transformer;

use Illuminate\Support\ServiceProvider;
use EGALL\Transformer\Contracts\Transformer as TransformerContract;
use EGALL\Transformer\Contracts\CollectionTransformer as CollectionTransformerContract;

/**
 * Transformer service provider.
 *
 * @package EGALL\Transformer
 * @author Erik Galloway <erik@mybarnapp.com>
 */
class TransformerServiceProvider extends ServiceProvider
{

    /**
     * Indicates if loading of the provider is deferred.
     *
     * @var bool
     */
    protected $defer = true;

    /**
     * Bootstrap the application services.
     *
     * @return void
     */
    public function boot()
    {
        //
    }

    /**
     * Register the application services.
     *
     * @return void
     */
    public function register()
    {

        $this->app->bind(TransformerContract::class, Transformer::class);
        $this->app->bind(CollectionTransformerContract::class, CollectionTransformer::class);
    }

    /**
     * Get the services provided by the provider.
     *
     * @return array
     */
    public function provides()
    {

        return [TransformerContract::class, CollectionTransformerContract::class];

    }
}

<?php

namespace EGALL\Transformer;

use Illuminate\Support\ServiceProvider;
use EGALL\Transformer\Contracts\Transformer as TransformerContract;
use EGALL\Transformer\Contracts\CollectionTransformer as CollectionTransformerContract;

/**
 * Transformer service provider.
 *
 * @package EGALL\Transformer
 * @author Erik Galloway <erik@mybarnapp.com>
 */
class TransformerServiceProvider extends ServiceProvider
{

    /**
     * Indicates if loading of the provider is deferred.
     *
     * @var bool
     */
    protected $defer = true;

    /**
     * Bootstrap the application services.
     *
     * @return void
     */
    public function boot()
    {
        //
    }

    /**
     * Register the application services.
     *
     * @return void
     */
    public function register()
    {

        $this->app->bind(TransformerContract::class, Transformer::class);
        $this->app->bind(CollectionTransformerContract::class, CollectionTransformer::class);
    }

    /**
     * Get the services provided by the provider.
     *
     * @return array
     */
    public function provides()
    {

        return [Transformer::class, CollectionTransformer::class];

    }
}

--- 
+++ 
@@ -52,7 +52,7 @@
     public function provides()
     {
 
-        return [Transformer::class, CollectionTransformer::class];
+        return [TransformerContract::class, CollectionTransformerContract::class];
 
     }
 }
Fix error in service provider..
