在运行工程时，突然出现此问题。首先，当然时一脸懵逼了。好在冷静下来后，看日志是jar包重复。关键是这个jar包我都没有见过。
Duplicate class org.intellij.lang.annotations.Flow found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.Identifier found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.JdkConstants found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.JdkConstants$AdjustableOrientation found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.JdkConstants$BoxLayoutAxis found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.JdkConstants$CalendarMonth found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.JdkConstants$CursorType found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.JdkConstants$FlowLayoutAlignment found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.JdkConstants$FontStyle found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.JdkConstants$HorizontalAlignment found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.JdkConstants$InputEventMask found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.JdkConstants$ListSelectionMode found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.JdkConstants$PatternFlags found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.JdkConstants$TabLayoutPolicy found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.JdkConstants$TabPlacement found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.JdkConstants$TitledBorderJustification found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.JdkConstants$TitledBorderTitlePosition found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.JdkConstants$TreeSelectionMode found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.Language found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.MagicConstant found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.Pattern found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.PrintFormat found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.PrintFormatPattern found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.RegExp found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.intellij.lang.annotations.Subst found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.jetbrains.annotations.Contract found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.jetbrains.annotations.Nls found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.jetbrains.annotations.NonNls found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.jetbrains.annotations.NotNull found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.jetbrains.annotations.Nullable found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.jetbrains.annotations.PropertyKey found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Duplicate class org.jetbrains.annotations.TestOnly found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
Go to the documentation to learn how to Fix dependency resolution errors.
后来仔细看Gradle依赖，发现了这个依赖
implementation 'org.jetbrains:annotations-java5:15.0'
这个jar包有什么作用呢。它是用于代码检查支持和代码文档。简单来说，就是检查我们的代码的jar包。我将它替换成如下
implementation 'org.jetbrains:annotations:13.0'
万事大吉了。冲突解决了。为什么替换成它呢。我是根据上面的报错提示写的。
Duplicate class org.intellij.lang.annotations.Flow found in modules annotations-13.0.jar (org.jetbrains:annotations:13.0) and annotations-java5-15.0.jar (org.jetbrains:annotations-java5:15.0)
这句话中括号里面的就是我们所需要的依赖了。至于为什么，我想是因为gradle版本问题吧。