build.gradle

import java.nio.file.Files

tasks.register('validate') {
    File folder = file('src/messages')
    Files.list(folder.toPath()).forEach {
        String fileName = it.toFile().getName();
        Properties properties = new Properties()
        properties.load(it.newInputStream())
        properties.each {
            if (it.key == null || it.key.toString().isBlank() || it.value == null) {
                throw new IllegalArgumentException('Failed validation on file ' + fileName)
            }
            String value = it.value.toString();
            boolean failed = false
            if (value.startsWith("\'") || value.startsWith("\"")) {
                failed = true
            } else if (value.count('{') != value.count('}')) {
                failed = true
            } else if (value.isBlank()) {
                failed = true
            }
            if (failed) {
                throw new IllegalArgumentException('Failed validation on file ' + fileName + ': ' + it.key)
            }
        }
    }
}