restore static blocks in protobuf

Author: diegomarquezp

google-http-client-protobuf/src/main/java/com/google/api/client/protobuf/ProtocolBuffers.java

@@ -37,15 +37,10 @@
 public class ProtocolBuffers {
 
   /** {@code "application/x-protobuf"} content type. */
-  public static final String CONTENT_TYPE;
+  public static final String CONTENT_TYPE = "application/x-protobuf";
 
   /** {@code "application/x-protobuffer"} content type. */
-  public static final String ALT_CONTENT_TYPE;
-
-  static {
-    CONTENT_TYPE = "application/x-protobuf";
-    ALT_CONTENT_TYPE = "application/x-protobuffer";
-  }
+  public static final String ALT_CONTENT_TYPE = "application/x-protobuffer";
 
   /**
    * Parses protocol buffer content from an input stream (closing the input stream) into a protocol