com.netease.nimlib.sdk.v2.message.attachment.V2NIMMessageCustomAttachment 成员列表

成员的完整列表，这些成员属于 com.netease.nimlib.sdk.v2.message.attachment.V2NIMMessageCustomAttachment,包括所有继承而来的类成员

getRaw()	com.netease.nimlib.sdk.v2.message.attachment.V2NIMMessageAttachment
parse(String attach)	com.netease.nimlib.sdk.v2.message.attachment.V2NIMMessageCustomAttachment