Can we use 'Box' in static region in Rust?

Question

I'm confused about the usage of Rust around static variables with Box Traits.

trait ContextBase {}

struct ContextA {}
impl ContextBase for ContextA {}
struct ContextB {}
impl ContextBase for ContextB {}

lazy_static! {
 static ref GLOBAL_CONTEXT: HashMap<&'static str, Box<ContextBase>> = HashMap::new();
}

I want to allow Context which implements the ContextBase traits. But compile results are like this.

error[E0277]: `(dyn context::ContextBase + 'static)` cannot be shared between threads safely
  --> src/context.rs:19:1
   |
19 | / lazy_static! {
20 | |   static ref GLOBAL_CONTEXT: HashMap<&'static str, Box<ContextBase>> = HashMap::new();
21 | | }
   | |_^ `(dyn context::ContextBase + 'static)` cannot be shared between threads safely
   |
   = help: the trait `std::marker::Sync` is not implemented for `(dyn context::ContextBase + 'static)`
   = note: required because of the requirements on the impl of `std::marker::Sync` for `std::ptr::Unique<(dyn context::ContextBase + 'static)>`
   = note: required because it appears within the type `std::boxed::Box<(dyn context::ContextBase + 'static)>`
   = note: required because it appears within the type `(&'static str, std::boxed::Box<(dyn context::ContextBase + 'static)>)`
   = note: required because of the requirements on the impl of `std::marker::Sync` for `hashbrown::raw::RawTable<(&'static str, std::boxed::Box<(dyn context::ContextBase + 'static)>)>`
   = note: required because it appears within the type `hashbrown::map::HashMap<&'static str, std::boxed::Box<(dyn context::ContextBase + 'static)>, std::collections::hash_map::RandomState>`
   = note: required because it appears within the type `std::collections::HashMap<&'static str, std::boxed::Box<(dyn context::ContextBase + 'static)>>`
   = note: required by `lazy_static::lazy::Lazy`
   = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

Can anyone help me resolve this issue??