I have used jhipster import-jdl my_file.jdl
Jhipster version V5.7.0
And content of that jdl file is(below(IDK application?config is not showing in code editor in stack overflow))
application {
    config {
        prodDatabaseType mysql
        buildTool maven
    }
}
entity Region {
    regionName String
}
entity Country {
    countryName String
}
// an ignored comment
/** not an ignored comment */
entity Location {
    streetAddress String,
    postalCode String,
    city String,
    stateProvince String
}
entity Department {
    departmentName String required
}
entity Task {
    title String,
    description String
}
entity Employee {
    firstName String,
    lastName String,
    email String,
    phoneNumber String,
    hireDate Instant,
    salary Long,
    commissionPct Long
}
entity Job {
    jobTitle String,
    minSalary Long,
    maxSalary Long
}
entity JobHistory {
    startDate Instant,
    endDate Instant,
    language Language
}
enum Language {
    FRENCH, ENGLISH, SPANISH
}
relationship OneToOne {
    Country{region} to Region
}
relationship OneToOne {
    Location{country} to Country
}
relationship OneToOne {
    Department{location} to Location
}
relationship ManyToMany {
    Job{task(title)} to Task{job}
}
relationship OneToMany {
    Employee{job} to Job,
    Department{employee} to Employee
}
relationship ManyToOne {
    Employee{manager} to Employee
}
relationship OneToOne {
    JobHistory{job} to Job,
    JobHistory{department} to Department,
    JobHistory{employee} to Employee
}
// Set pagination options
paginate JobHistory, Employee with infinite-scroll
paginate Job with pagination
// Use Data Transfert Objects (DTO)
// dto * with mapstruct
// Set service options to all except few
//service all with serviceImpl except Employee, Job
// Set an angular suffix
// angularSuffix * with mySuffix`
And cmd showing
DEBUG!  importState exportedEntities: 0
DEBUG!  importState exportedApplications: 1  
DEBUG!  importState exportedDeployments: 0
INFO! No change in entity configurations, no entities were updated.
When I am not mentioning application > config details, it is giving error as
Error: The JDL object and the database type are both mandatory.        
ERROR! Error while parsing applications and entities from the JDL Error: The JDL object and the database type are both mandatory.
Can anyone tell me what I am doing wrong ?