Recibo el error org.json.JSONException: no hay valor para PROJECT_NAME Este es mi json

{"PROJECTS":[ 
         {
            "PROJECT_NUMBER": "2062",
            "PROJECT_NAME": "OPW 51183"
         },
         {
            "PROJECT_NUMBER": "404",
            "PROJECT_NAME": "404"
         },
         {
            "PROJECT_NUMBER": "2125",
            "PROJECT_NAME": "OPW 50016"
         },
         {
            "PROJECT_NUMBER": ""
         },
         {
            "PROJECT_NUMBER": "2130",
            "PROJECT_NAME": "OPW 51151 63rd & Shirley SEW S"
         },
         {
            "PROJECT_NUMBER": "2159",
            "PROJECT_NAME": "OPW 51226"
         }
        ]

    }

y el bacalao es:

for (int i = 0; i < innerProjectarray.length(); i++) 
    {

JSONObject obj=innerProjectarray.getJSONObject(i);
String projectnumber1=obj.getString("PROJECT_NUMBER");
String projectname1=obj.getString("PROJECT_NAME");
        }

¿Hay alguna forma de encontrar la clave? Si la clave no existe, entonces np necesita obtener el valor de una cadena en particular.