具体错误：
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.0:testCompile (default-testCompile) on project teavm-tests: Fatal error compiling: 无效的目标发行版: 11 -> [Help 1] [ERROR] [ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch. [ERROR] Re-run Maven using the -X switch to enable full debug logging. [ERROR] [ERROR] For more information about the errors and possible solutions, please read the following articles: [ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException [ERROR] [ERROR] After correcting the problems, you can resume the build with the command [ERROR] mvn <args> -rf :teavm-tests
打开对应的pom.xml，有如下内容：
<plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>${maven-compiler-plugin.version}</version> <configuration> <source>${java-tests.version}</source> <target>${java-tests.version}</target> </configuration> </plugin>
把source/target改为1.8是不对的。在pom.xml中应该有类似如下的配置：
<java.version>1.8</java.version> <java-tests.version>11</java-tests.version>
吾把11改成1.8，就报一些接口找不到。所以，吾解决办法是提高了java.version。
