ANTLR4在导入时找不到语法

我正在尝试将我的ANTLR4语法分割到多个文件中,以便更轻松地测试它们,我正在使用gradle作为java项目中的构建工具。

这两种语法都通过separate正确编译,但当我将导入添加到主语法时,我会出现下一个编译错误

inherited 语法看起来像:

grammar SpecflowScenario;

@header {
    package kanekotic.specflow.rider;
}

scenario
    : 'Scenario: ';

和 main 语法看起来像:

grammar SpecflowFeature;

import SpecflowScenario;

@header {
    package kanekotic.specflow.rider;
}

file returns [List<String> values]
    @init { $values = new ArrayList<String>(); }
    : 'Feature: ' EOF;

这个 gradle.build 看起来像:

plugins {
    id "org.jetbrains.intellij" version "0.1.10"
}

apply plugin: 'org.jetbrains.intellij'
apply plugin: 'java'
apply plugin: 'antlr'

sourceCompatibility = JavaVersion.VERSION_1_8
targetCompatibility = JavaVersion.VERSION_1_8

intellij {
    version '143.2370.31'
    pluginName 'Specflow Rider'
}

group 'kanekotic.specflow.rider'
version '0.1'

repositories {
    mavenCentral()
    jcenter()
}

dependencies {
    antlr "org.antlr:antlr4:4.5"
    testCompile 'junit:junit:4.12'
    testCompile "org.mockito:mockito-core:2.+"
} 

所有开源代码都在下一个链接中: https://github.com/kanekotic/Specflow.Rider/tree/antlr4_multiple_grammar