# Objective

Follow-up to #17615.

Bevy's entity collection types like `EntityHashSet` no longer implement
serde's `Serialize` and `Deserialize` after becoming newtypes instead of
type aliases in #16912. This broke some types that support serde for me
in Avian.

I also missed creating const constructors for `EntityIndexMap` and
`EntityIndexSet` in #17615. Oops!

## Solution

Implement `Serialize` and `Deserialize` for Bevy's entity collection
types, and add const constructors for `EntityIndexMap` and
`EntityIndexSet`.

I didn't implement `ReflectSerialize` or `ReflectDeserialize` here,
because I had some trouble fixing the resulting errors, and they were
not implemented previously either.

…17615)

# Objective

bevyengine#16912 turned `EntityHashMap` and `EntityHashSet` into proper newtypes
instead of type aliases. However, this removed the ability to create
these collections in const contexts; previously, you could use
`EntityHashSet::with_hasher(EntityHash)`, but it doesn't exist anymore.

## Solution

Make `EntityHashMap::new` and `EntityHashSet::new` const methods.

…e#17620)

# Objective

Follow-up to bevyengine#17615.

Bevy's entity collection types like `EntityHashSet` no longer implement
serde's `Serialize` and `Deserialize` after becoming newtypes instead of
type aliases in bevyengine#16912. This broke some types that support serde for me
in Avian.

I also missed creating const constructors for `EntityIndexMap` and
`EntityIndexSet` in bevyengine#17615. Oops!

## Solution

Implement `Serialize` and `Deserialize` for Bevy's entity collection
types, and add const constructors for `EntityIndexMap` and
`EntityIndexSet`.

I didn't implement `ReflectSerialize` or `ReflectDeserialize` here,
because I had some trouble fixing the resulting errors, and they were
not implemented previously either.

…17615)

# Objective

bevyengine#16912 turned `EntityHashMap` and `EntityHashSet` into proper newtypes
instead of type aliases. However, this removed the ability to create
these collections in const contexts; previously, you could use
`EntityHashSet::with_hasher(EntityHash)`, but it doesn't exist anymore.

## Solution

Make `EntityHashMap::new` and `EntityHashSet::new` const methods.

…e#17620)

# Objective

Follow-up to bevyengine#17615.

Bevy's entity collection types like `EntityHashSet` no longer implement
serde's `Serialize` and `Deserialize` after becoming newtypes instead of
type aliases in bevyengine#16912. This broke some types that support serde for me
in Avian.

I also missed creating const constructors for `EntityIndexMap` and
`EntityIndexSet` in bevyengine#17615. Oops!

## Solution

Implement `Serialize` and `Deserialize` for Bevy's entity collection
types, and add const constructors for `EntityIndexMap` and
`EntityIndexSet`.

I didn't implement `ReflectSerialize` or `ReflectDeserialize` here,
because I had some trouble fixing the resulting errors, and they were
not implemented previously either.