Some problems were encountered while building the effective model for com.ecjtu:adopt:war:1.0-SNAPSHOT 'dependencies.dependency.(groupId:artifactId:type:classifier)' must be unique: com.fasterxml.jackson.core:jackson-databind:jar -> duplicate declaration of version 2.9.9.3 @ line 159, column 21 It is highly recommended to fix these problems because they threaten the stability of your build. For this reason, future Maven versions might no longer support building such malformed projects.

解决办法：
检查pom文件，可能有重复的dependency,将重复的去除即可