Why can't I use -options EmitDefaults and -JsonCompatible about powershell-yaml HOT 5 CLOSED

PS /home/gabriel> $a = @{"true"= $true; "false"= $false}
PS /home/gabriel> ConvertTo-Yaml -JsonCompatible $a
{"true": true, "false": false}

PS /home/gabriel> ConvertTo-Yaml $a                
"true": true
"false": false

PS /home/gabriel> ConvertTo-Yaml $a -Options EmitDefaults
"true": true
"false": false

PS /home/gabriel> ConvertTo-Yaml $a                      
"true": true
"false": false

#Requires -Module powershell-yaml
using namespace YamlDotNet.Serialization
class MyClass {
    [YamlMemberAttribute(Order = 0)]
    [string] $Prop1

    [YamlMemberAttribute(Order = 1)]
    [bool] $PropTrue = $true

    [YamlMemberAttribute(Order = 2)]
    [bool] $PropFalse = $false

    MyClass() {
        $this.Prop1 = "MyClassInstance"
    }

    [string] ToYaml() {
        return ($this | ConvertTo-Yaml -Options EmitDefaults)
    }

    [string] ToYamlNoDefaults() {
        return ($this | ConvertTo-Yaml)
    }

    [string] ToJSON() {
        return ($this | ConvertTo-Yaml -JsonCompatible)
    }

    [string] ToString() {
        return $this.ToYaml()
    }
}
"==================================`r`n`r`n"

[MyClass]::new()
"==================================`r`n`r`n"

[MyClass]::new().ToYaml()

"==================================`r`n`r`n"
[MyClass]::new().ToYamlNoDefaults()

"==================================`r`n`r`n"
[MyClass]::new().ToJSON()

#Requires -Module powershell-yaml
using namespace YamlDotNet.Serialization
class MyClass {
    [YamlMemberAttribute(Order = 0)]
    [string] $Prop1

    [YamlMemberAttribute(Order = 1)]
    [bool] $PropTrue = $true

    [YamlMemberAttribute(Order = 2)]
    [bool] $PropFalse = $false

    [YamlMemberAttribute(Order = 3)]
    [int] $PropInt = 0


    MyClass() {
        $this.Prop1 = "MyClassInstance"
    }

    [string] ToYaml() {
        return (ConvertTo-Yaml -Options EmitDefaults $this)
    }

    [string] ToYamlNoDefaults() {
        return (ConvertTo-Yaml $this)
    }

    [string] ToJSON() {
        return (ConvertTo-Yaml -Options JsonCompatible,EmitDefaults $this)
    }

    [string] ToString() {
        return $this.ToYaml()
    }
}