Support suppressing the objc package prefix checks on a list of files.

src/google/protobuf/compiler/objectivec/objectivec_generator.cc

diff --git a/src/google/protobuf/compiler/objectivec/objectivec_generator.cc b/src/google/protobuf/compiler/objectivec/objectivec_generator.cc
index e0597cc..25338ad 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_generator.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_generator.cc
@@ -89,6 +89,12 @@
       // There is no validation that the prefixes are good prefixes, it is
       // assumed that they are when you create the file.
       generation_options.expected_prefixes_path = options[i].second;
+    } else if (options[i].first == "expected_prefixes_suppressions") {
+      // A semicolon delimited string that lists the paths of .proto files to
+      // exclude from the package prefix validations (expected_prefixes_path).
+      // This is provided as an "out", to skip some files being checked.
+      SplitStringUsing(options[i].second, ";",
+                       &generation_options.expected_prefixes_suppressions);
     } else if (options[i].first == "generate_for_named_framework") {
       // The name of the framework that protos are being generated for. This
       // will cause the #import statements to be framework based using this

src/google/protobuf/compiler/objectivec/objectivec_helpers.cc

diff --git a/src/google/protobuf/compiler/objectivec/objectivec_helpers.cc b/src/google/protobuf/compiler/objectivec/objectivec_helpers.cc
index 0afa6fb..5357e94 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_helpers.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_helpers.cc
@@ -76,6 +76,10 @@
   if (file_path) {
     expected_prefixes_path = file_path;
   }
+  const char* suppressions = getenv("GPB_OBJC_EXPECTED_PACKAGE_PREFIXES_SUPPRESSIONS");
+  if (suppressions) {
+    SplitStringUsing(suppressions, ";", &expected_prefixes_suppressions);
+  }
 }
 
 namespace {
@@ -1169,6 +1173,15 @@
   }
 
   for (int i = 0; i < files.size(); i++) {
+    bool should_skip =
+      (std::find(generation_options.expected_prefixes_suppressions.begin(),
+                 generation_options.expected_prefixes_suppressions.end(),
+                 files[i]->name())
+          != generation_options.expected_prefixes_suppressions.end());
+    if (should_skip) {
+      continue;
+    }
+
     bool is_valid =
         ValidateObjCClassPrefix(files[i],
                                 generation_options.expected_prefixes_path,

src/google/protobuf/compiler/objectivec/objectivec_helpers.h

diff --git a/src/google/protobuf/compiler/objectivec/objectivec_helpers.h b/src/google/protobuf/compiler/objectivec/objectivec_helpers.h
index e7f21f2..3ec465f 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_helpers.h
+++ b/src/google/protobuf/compiler/objectivec/objectivec_helpers.h
@@ -50,6 +50,7 @@
 struct Options {
   Options();
   string expected_prefixes_path;
+  std::vector<string> expected_prefixes_suppressions;
   string generate_for_named_framework;
   string named_framework_to_proto_path_mappings_path;
 };