I'm using ES 5.1.2. I want to do some tests so I need to install from source. I clone source code and `mvn package` to create few jar files.
`bin/elasticsearch-plugin install file:///Users/rayjcwu/repo/search-guard/target/search-guard-5-5.1.2-12-SNAPSHOT.jar`
will show
```
-> Downloading file:///Users/rayjcwu/repo/search-guard/target/search-guard-5-5.1.2-12-SNAPSHOT.jar
[=================================================] 100%
ERROR: `elasticsearch` directory is missing in the plugin zip
```
but `bin/elasticsearch-plugin install -b com.floragunn:search-guard-5:5.1.2-11` works fine. I open the search-guard-5 jar file in /plugins, didn't see any /elasticsearch directory in it.
Does anyone know what elasticsearch directory does it refer to?