Copy client jars instead of moving them

Moving the dependent jars instead of copying breaks downstream builds
that rely on the jars existing for compilation. This commit modifies
these moves to be copies.

buildSrc/src/main/groovy/org/elasticsearch/gradle/plugin/PluginBuildPlugin.groovy

@@ -157,21 +157,21 @@ public class PluginBuildPlugin extends BuildPlugin {
         clientJar.doFirst {
             Path jarFile = project.jar.outputs.files.singleFile.toPath()
             String clientFileName = jarFile.fileName.toString().replace(project.version, "client-${project.version}")
-            Files.move(jarFile, jarFile.resolveSibling(clientFileName), StandardCopyOption.REPLACE_EXISTING)
+            Files.copy(jarFile, jarFile.resolveSibling(clientFileName), StandardCopyOption.REPLACE_EXISTING)
 
             String pomFileName = jarFile.fileName.toString().replace('.jar', '.pom')
             String clientPomFileName = clientFileName.replace('.jar', '.pom')
-            Files.move(jarFile.resolveSibling(pomFileName), jarFile.resolveSibling(clientPomFileName),
+            Files.copy(jarFile.resolveSibling(pomFileName), jarFile.resolveSibling(clientPomFileName),
                     StandardCopyOption.REPLACE_EXISTING)
 
             String sourcesFileName = jarFile.fileName.toString().replace('.jar', '-sources.jar')
             String clientSourcesFileName = clientFileName.replace('.jar', '-sources.jar')
-            Files.move(jarFile.resolveSibling(sourcesFileName), jarFile.resolveSibling(clientSourcesFileName),
+            Files.copy(jarFile.resolveSibling(sourcesFileName), jarFile.resolveSibling(clientSourcesFileName),
                     StandardCopyOption.REPLACE_EXISTING)
 
             String javadocFileName = jarFile.fileName.toString().replace('.jar', '-javadoc.jar')
             String clientJavadocFileName = clientFileName.replace('.jar', '-javadoc.jar')
-            Files.move(jarFile.resolveSibling(javadocFileName), jarFile.resolveSibling(clientJavadocFileName),
+            Files.copy(jarFile.resolveSibling(javadocFileName), jarFile.resolveSibling(clientJavadocFileName),
                     StandardCopyOption.REPLACE_EXISTING)
         }
         project.assemble.dependsOn(clientJar)