Whenever spawning in an item with the HideFlags data, it doesn't hide any tags. Enchantments, if Unbreakable, and Attribute modifiers can still be seen. Code tested: /give @p minecraft:iron_sword 1 0 {HideFlags:7,AttributeModifiers:[

{AttributeName:"generic.maxHealth",Name:"generic.maxHealth",Amount:2,Operation:0,UUIDLeast:894654,UUIDMost:2872}

],Unbreakable:1,ench:[

{id:16,lvl:5}

]}

In Vanilla, it results in a sword with sharpness 5, unbreakable, and adds one heart to the player when held, but none of that information readily available.

In Spigot, it is the same sword statistically, but you can see the attribute modifier, the enchantment, and can see it is unbreakable.