JDL: Found groupable relationship "OneToOne"

Question

I am new to JHipster and am creating a new project with the following Entity definition:

enum AccountType {
    CHECKING, SAVINGS
}

enum TransactionType {
    CHECK, DEPOSIT, WITHDRAWAL
}

enum EnvelopeType {
    INCOME, EXPENSE
}

// The name 'Account' is a reserved keyword and can not be used as an entity class name.
entity Ledger {
    name String required
    type AccountType
    memo String
    accountNumber String
    routingNumber String
}

entity Envelope {
    name String required
    type EnvelopeType
    memo String
}

entity Transaction {
    name String required
    type TransactionType
    memo String
    amount BigDecimal
}

relationship OneToOne {
    Transaction to Envelope
}

relationship OneToMany {
  Ledger to Transaction
}

Within VS Code, I get the following warnings:

• Found groupable relationship "OneToOne"
• Found groupable relationship "OneToMany"

It is unclear what each of these relationships can be grouped with to quash the warnings.