`©` in license header file converts to � in source files

[nixel2007]

Hello!

I have a header.txt file with © symbol in it. If I run licenseFormat task, this symbol is inserted as � in java source files.

build.gradle.kts configuration:

license {
    header(file("license/HEADER.txt"))
    charset("UTF-8")
    newLine(false)
    ext["year"] = "2018-" + Calendar.getInstance().get(Calendar.YEAR)
    ext["name"] = "Alexey Sosnoviy <labotamy@gmail.com>, Nikita Gryzlov <nixel2007@gmail.com>"
    ext["project"] = "BSL Language Server"
    exclude("**/*.properties")
    exclude("**/*.xml")
    exclude("**/*.json")
    exclude("**/*.bsl")
    exclude("**/*.os")
    exclude("**/*.txt")
    exclude("**/*.java.orig")
    exclude("**/*.impl")
    exclude("**/*.mockito.plugins.MockMaker")
}

HEADER.txt saved with UTF-8 encoding. plugin version 0.6.0