test/org/apache/pig/builtin/avro/schema/recordsWithDoubleUnderscores.avsc

{
  "name" : "recordsWithDoubleUnderscores",
  "namespace" : "org.apache.pig.test.builtin",
  "type" : "record",
  "fields" : [
    {"name" : "A__key", "type" : ["null", "string"]},
    {"name" : "B__C__intValue", "type" : ["null", "int"]}
  ]
}