Execution failed for task ':signMavenPublication' (jar file not generated)

$ ./gradlew publish

* What went wrong:
Execution failed for task ':signMavenPublication'.
> java.io.FileNotFoundException: /Users/kael/Codes/java/fastjson-protobuf/build/libs/fastjson-protobuf-0.1.3.jar (No such file or directory)

The build.gradle file can be found here https://github.com/kaelzhang/java-fastjson-protobuf/blob/master/build.gradle

I’ve added the java-library plugin, but ./gradlew publish will not generate the jar file. And only the xxx-source.jar file is found in the build/libs directory

$ gradle --version

Gradle 4.9

Build time:   2018-07-16 08:14:03 UTC
Revision:     efcf8c1cf533b03c70f394f270f46a174c738efc

Kotlin DSL:   0.18.4
Kotlin:       1.2.41
Groovy:       2.4.12
Ant:          Apache Ant(TM) version 1.9.11 compiled on March 23 2018
JVM:          1.8.0_144 (Oracle Corporation 25.144-b01)
OS:           Mac OS X 10.13.6 x86_64