Plugin Error

[SrinivReddy]

while executing marathon --plugin_dir=/etc/marathon/marathon-example-plugins-1.3.5/target/pack/lib --plugin_conf=/etc/marathon/plugins/configuration.json --master=http://master-ip:5050

i am getting below error can you please help me out.

ERROR Terminating due to uncaught exception in thread main:1 (mesosphere.marathon.MarathonApp:main)
com.google.inject.CreationException: Unable to create injector, see the following errors:

1. Error injecting constructor, mesosphere.marathon.WrongConfigurationException: Plugin not found: PluginDefinition(authentication,mesosphere.marathon.plugin.auth.Authenticator,mesosphere.marathon.example.plugin.auth.ExampleAuthenticator,None,Some({"users"...........

configuration.json file is below, implementation filed what to mention in exampleAuthorizer, Authenticator....
{
"plugins": {
"authorization": {
"plugin": "mesosphere.marathon.plugin.auth.Authorizer",
"implementation": "mesosphere.marathon.example.plugin.auth.ExampleAuthorizer"
},
"authentication": {
"plugin": "mesosphere.marathon.plugin.auth.Authenticator",
"implementation": "mesosphere.marathon.example.plugin.auth.ExampleAuthenticator",
"configuration": {
"users": [
{
"user": "user",
"password": "user",
"permissions": [
{ "allowed": "create", "on": "/dev/" },
{ "allowed": "view", "on": "/dev/" }
]
},
{
"user": "user1",
"password": "user1",
"permissions": [
{ "allowed": "update", "on": "/prod/" },
{ "allowed": "delete", "on": "/prod/" }
]
},
{
"user": "user2",
"password": "user2",
"permissions": [
{ "allowed": "create", "on": "/prod/" },
{ "allowed": "update", "on": "/prod/" },
{ "allowed": "delete", "on": "/dev/" },
{ "allowed": "view", "on": "/dev/" }
]
},
{
"user": "user3",
"password": "user3",
"permissions": [
{ "allowed": "create", "on": "/" },
{ "allowed": "update", "on": "/" },
{ "allowed": "delete", "on": "/" },
{ "allowed": "view", "on": "/" }
]
}
]
}
}
}
}