error: plug-in not found: ErrorProne

[ygmkk]

my gradle setting as flow:
buildscript {
dependencies {
classpath 'net.ltgt.gradle:gradle-errorprone-plugin:1.3.0'
}
}
apply plugin: "net.ltgt.errorprone"
dependencies {
errorproneJavac("com.google.errorprone:javac:9+181-r4173-1")
}

but i get a build error:
error: plug-in not found: ErrorProne

thanks~

[ygmkk]

sorry i forget to add :
dependencies {
errorprone("com.google.errorprone:error_prone_core:$errorproneVersion")
}