Warn if building an empty list of targets

    The syntax of bazel's build command is `bazel build <options> <targets>`.
    In particular, just `bazel build` is a legitimate request to build
    the empty list of targets. Nevertheless, some users get confused
    by this behavior and requested that a warning be added. Do as
    requested.

    Fixes #6811.

    Change-Id: I83f9a9e18f01f657242fc06f3ac09d68a0256ec7
    PiperOrigin-RevId: 233765339

dataset/GitHub_Java/bazelbuild.bazel/src/main/java/com/google/devtools/build/lib/runtime/commands/BuildCommand.java

@@ -79,9 +79,7 @@ public BlazeCommandResult exec(CommandEnvironment env, OptionsParsingResult opti
                   "Usage: "
                       + runtime.getProductName()
                       + " build <options> <targets>."
-                      + "\nInvoke `"
-                      + runtime.getProductName()
-                      + " help build` for full description of usage and options."
+                      + "\nInvoke `bazel help build` for full description of usage and options."
                       + "\nYour request is correct, but requested an empty set of targets."
                       + " Nothing will be built."));
     }