open fun addProperty(key: String!, value: String!): Unit
Add property to balloon model.
key - String!: property
value - String!: property
open fun addProperty(key: String!, value: Int): Unit
Add int property to balloon model.
key - String!: property
value - Int: property
open fun addProperty(key: String!, value: Long): Unit
Add long property to balloon model.
key - String!: property
value - Long: property