Rest Body Content contains junk with HeapByteBuf

The code at https://github.com/infinispan/infinispan/blob/cd3a25e6caffd719c624727b2352a426f34f79e1/server/rest/src/main/java/org/infinispan/rest/ByteBufContentSource.java#L26 returns the entire byte[]. Instead it should be returning a copy if the offset !=0 and readableBytes() != length.