Add more public modifiers

Author: STAR-ZERO

src/google/protobuf/compiler/java/message.cc

@@ -1357,7 +1357,7 @@ void ImmutableMessageGenerator::GenerateKotlinOrNull(io::Printer* printer) const
     const FieldDescriptor* field = descriptor_->field(i);
     if (field->has_presence() && GetJavaType(field) == JAVATYPE_MESSAGE) {
       printer->Print(
-          "val $full_classname$OrBuilder.$camelcase_name$OrNull: $full_name$?\n"
+          "public val $full_classname$OrBuilder.$camelcase_name$OrNull: $full_name$?\n"
           "  get() = if (has$name$()) get$name$() else null\n\n",
           "full_classname", name_resolver_->GetClassName(descriptor_, true),
           "camelcase_name", context_->GetFieldGeneratorInfo(field)->name,

src/google/protobuf/compiler/java/message_lite.cc

@@ -830,7 +830,7 @@ void ImmutableMessageLiteGenerator::GenerateKotlinOrNull(io::Printer* printer) c
     const FieldDescriptor* field = descriptor_->field(i);
     if (field->has_presence() && GetJavaType(field) == JAVATYPE_MESSAGE) {
       printer->Print(
-          "val $full_classname$OrBuilder.$camelcase_name$OrNull: "
+          "public val $full_classname$OrBuilder.$camelcase_name$OrNull: "
           "$full_name$?\n"
           "  get() = if (has$name$()) get$name$() else null\n\n",
           "full_classname", name_resolver_->GetClassName(descriptor_, true),