Use message name as defined in php runtime.

php/src/Google/Protobuf/Internal/GPBUtil.php

@@ -270,7 +270,7 @@ class GPBUtil
         $name,
         $file_proto)
     {
-        $classname = implode('_', array_map('ucwords', explode('.', $name)));
+        $classname = implode('_', explode('.', $name));
         return static::getClassNamePrefix($classname, $file_proto) . $classname;
     }
 

php/src/Google/Protobuf/Internal/Message.php

@@ -76,6 +76,9 @@ class Message
         }
         $pool = DescriptorPool::getGeneratedPool();
         $this->desc = $pool->getDescriptorByClassName(get_class($this));
+        if (is_null($this->desc)) {
+            user_error(get_class($this) . "is not found in descriptor pool.");
+        }
         foreach ($this->desc->getField() as $field) {
             $setter = $field->getSetter();
             if ($field->isMap()) {

php/tests/generated_class_test.php

@@ -14,6 +14,8 @@ use Foo\TestIncludePrefixMessage;
 use Foo\TestMessage;
 use Foo\TestMessage_Sub;
 use Foo\TestReverseFieldOrder;
+use Foo\testLowerCaseMessage;
+use Foo\testLowerCaseEnum;
 use Php\Test\TestNamespace;
 
 class GeneratedClassTest extends TestBase
@@ -715,4 +717,14 @@ class GeneratedClassTest extends TestBase
         $this->assertSame("abc", $m->getB());
         $this->assertNotSame("abc", $m->getA());
     }
+
+    #########################################################
+    # Test Reverse Field Order.
+    #########################################################
+
+    public function testLowerCase()
+    {
+        $m = new testLowerCaseMessage();
+        $n = testLowerCaseEnum::VALUE;
+    }
 }

php/tests/memory_leak_test.php

@@ -23,6 +23,8 @@ require_once('generated/Foo/TestPhpDoc.php');
 require_once('generated/Foo/TestRandomFieldOrder.php');
 require_once('generated/Foo/TestReverseFieldOrder.php');
 require_once('generated/Foo/TestUnpackedMessage.php');
+require_once('generated/Foo/testLowerCaseMessage.php');
+require_once('generated/Foo/testLowerCaseEnum.php');
 require_once('generated/GPBMetadata/Proto/Test.php');
 require_once('generated/GPBMetadata/Proto/TestEmptyPhpNamespace.php');
 require_once('generated/GPBMetadata/Proto/TestInclude.php');

php/tests/proto/test.proto

@@ -192,3 +192,10 @@ message TestReverseFieldOrder {
   repeated int32 a = 2;
   string b = 1;
 }
+
+message testLowerCaseMessage {
+}
+
+enum testLowerCaseEnum {
+  VALUE = 0;
+}