fields are now deleted when the val is empty .... among other changes

Cargo.lock

@@ -288,6 +288,7 @@ dependencies = [
  "bitflags",
  "bytes 1.2.1",
  "futures-util",
+ "headers",
  "http",
  "http-body",
  "hyper",
@@ -1280,6 +1281,31 @@ version = "0.12.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8a9ee70c43aaf417c914396645a0fa852624801b24ebb7ae78fe8272889ac888"
 
+[[package]]
+name = "headers"
+version = "0.3.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f3e372db8e5c0d213e0cd0b9be18be2aca3d44cf2fe30a9d46a65581cd454584"
+dependencies = [
+ "base64",
+ "bitflags",
+ "bytes 1.2.1",
+ "headers-core",
+ "http",
+ "httpdate",
+ "mime",
+ "sha1 0.10.5",
+]
+
+[[package]]
+name = "headers-core"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e7f66481bfee273957b1f20485a4ff3362987f85b2c236580d81b4eb7a326429"
+dependencies = [
+ "http",
+]
+
 [[package]]
 name = "heapless"
 version = "0.7.16"
@@ -2530,6 +2556,17 @@ dependencies = [
  "sha1_smol",
 ]
 
+[[package]]
+name = "sha1"
+version = "0.10.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f04293dc80c3993519f2d7f6f511707ee7094fe0c6d3406feb330cdb3540eba3"
+dependencies = [
+ "cfg-if",
+ "cpufeatures",
+ "digest 0.10.5",
+]
+
 [[package]]
 name = "sha1_smol"
 version = "1.0.0"
@@ -2693,7 +2730,7 @@ dependencies = [
  "serde",
  "serde_derive",
  "serde_json",
- "sha1",
+ "sha1 0.6.1",
  "syn",
 ]