Prepare for 7.1 release (#1593)

Making the example build under Bazel 9 needed protobuf pinned back to
33.4 (35.0 requires Bazel >= 8, which was breaking the 7.x cell), an
explicit `rules_java` bazel_dep, and `load` statements for `java_library`
and `java_proto_library` since Bazel 9 no longer autoloads them.
diff --git a/.bcr/presubmit.yml b/.bcr/presubmit.yml
index e7b3614..1b29ba8 100644
--- a/.bcr/presubmit.yml
+++ b/.bcr/presubmit.yml
@@ -31,6 +31,7 @@
     - macos_arm64
     - windows
     bazel:
+    - 9.x
     - 8.x
     - 7.x
   tasks:
diff --git a/MODULE.bazel b/MODULE.bazel
index cf48fe5..cb0f095 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -1,6 +1,6 @@
 module(
     name = "rules_jvm_external",
-    version = "7.0",
+    version = "7.1",
     bazel_compatibility = [">=7.0.0"],
 )
 
diff --git a/examples/java-export/MODULE.bazel b/examples/java-export/MODULE.bazel
index 3b35154..951674f 100644
--- a/examples/java-export/MODULE.bazel
+++ b/examples/java-export/MODULE.bazel
@@ -1,8 +1,9 @@
 module(name = "rules_jvm_external_example_java_export")
 
-protobuf_version = "35.0"
+protobuf_version = "33.4"
 
 bazel_dep(name = "protobuf", version = protobuf_version)
+bazel_dep(name = "rules_java", version = "9.3.0")
 bazel_dep(name = "rules_jvm_external", version = "ignored")
 bazel_dep(name = "rules_proto", version = "7.1.0")
 
diff --git a/examples/java-export/maven_install.json b/examples/java-export/maven_install.json
index 86575f0..b0ff5a7 100644
--- a/examples/java-export/maven_install.json
+++ b/examples/java-export/maven_install.json
@@ -6,7 +6,7 @@
     "com.google.errorprone:error_prone_annotations": 1790047777,
     "com.google.guava:guava": -249069712,
     "com.google.j2objc:j2objc-annotations": -26400317,
-    "com.google.protobuf:protobuf-java": 1247529435,
+    "com.google.protobuf:protobuf-java": 1906581597,
     "repositories": -1949687017
   },
   "__RESOLVED_ARTIFACTS_HASH": {
@@ -23,8 +23,8 @@
     "com.google.guava:listenablefuture": 1079558157,
     "com.google.j2objc:j2objc-annotations": -1008747351,
     "com.google.j2objc:j2objc-annotations:jar:sources": -1518668002,
-    "com.google.protobuf:protobuf-java": 1331070778,
-    "com.google.protobuf:protobuf-java:jar:sources": 133270104,
+    "com.google.protobuf:protobuf-java": 1957269082,
+    "com.google.protobuf:protobuf-java:jar:sources": 1812626912,
     "org.jspecify:jspecify": 117231129,
     "org.jspecify:jspecify:jar:sources": -2134060298
   },
@@ -79,10 +79,10 @@
     },
     "com.google.protobuf:protobuf-java": {
       "shasums": {
-        "jar": "400621a8f0aac52fab7ec88f492edd356f5a4355caa8f92028f217a8b5e4ac3b",
-        "sources": "63798a62a5f62575c814b92b1b951252bfd379ebe8207610db41622e03b007dc"
+        "jar": "3ca892fd6ea8b37d01bb6917dbc0bf2637548b756753f65a28d4f1d4d982347f",
+        "sources": "ed30fe6a51c7c15a6f123448304c97185f2039f2aeca9d5e3b4f53de3a4c813c"
       },
-      "version": "4.35.0"
+      "version": "4.33.4"
     },
     "org.jspecify:jspecify": {
       "shasums": {
diff --git a/examples/java-export/src/main/java/com/github/bazelbuild/rulesjvmexternal/example/export/BUILD b/examples/java-export/src/main/java/com/github/bazelbuild/rulesjvmexternal/example/export/BUILD
index ab6a2b6..09af32d 100644
--- a/examples/java-export/src/main/java/com/github/bazelbuild/rulesjvmexternal/example/export/BUILD
+++ b/examples/java-export/src/main/java/com/github/bazelbuild/rulesjvmexternal/example/export/BUILD
@@ -1,4 +1,5 @@
 load("@bazel_tools//tools/build_defs/pkg:pkg.bzl", "pkg_tar")
+load("@rules_java//java:java_library.bzl", "java_library")
 load("@rules_jvm_external//:defs.bzl", "artifact")
 
 java_library(
diff --git a/examples/java-export/src/main/proto/BUILD b/examples/java-export/src/main/proto/BUILD
index 64ac2e8..548e9ae 100644
--- a/examples/java-export/src/main/proto/BUILD
+++ b/examples/java-export/src/main/proto/BUILD
@@ -1,3 +1,4 @@
+load("@rules_java//java:defs.bzl", "java_library", "java_proto_library")
 load("@rules_jvm_external//:defs.bzl", "artifact")
 load("@rules_proto//proto:defs.bzl", "proto_library")