CopyProject: Remove @Singleton annotation

The class has a Writer member that is non-final and can be set by
callers, so it should not be annotated as @Singleton.

Change-Id: I47c8a4d5bda312ea18a222fb317d545b13d35b70

src/main/java/com/googlesource/gerrit/plugins/importer/CopyProject.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/importer/CopyProject.java b/src/main/java/com/googlesource/gerrit/plugins/importer/CopyProject.java
index cc33fd9..7d9f712 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/importer/CopyProject.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/importer/CopyProject.java
@@ -37,7 +37,6 @@
 import com.google.gwtorm.server.OrmException;
 import com.google.inject.Inject;
 import com.google.inject.Provider;
-import com.google.inject.Singleton;
 
 import com.googlesource.gerrit.plugins.importer.CopyProject.Input;
 
@@ -48,7 +47,6 @@
 import java.io.PrintWriter;
 import java.io.Writer;
 
-@Singleton
 @RequiresCapability(CopyProjectCapability.ID)
 class CopyProject implements RestModifyView<ProjectResource, Input>,
     UiAction<ProjectResource> {