[Properties] Support property key being both value and a prefix for other keys

[mgroth0]

What is your use-case and why do you need this feature?

In gradle.properties, we can have the following properties:

org.gradle.unsafe.configuration-cache=true
org.gradle.unsafe.configuration-cache.max-problems=0

This creates a conflict. Because we can't have both at the same time:

@Serializable
data class UnsafeProperties(
    val `configuration-cache`: Boolean
)

@Serializable
data class UnsafeProperties(
    val `configuration-cache`: ConfigCacheProps
)
@Serializable
data class ConfigCacheProps(
    val `max-problems`: Int
)

Describe the solution you'd like

Maybe something like this?

@Serializable
data class UnsafeProperties(
    val `configuration-cache`: Pair<Boolean,ConfigCacheProps>
)

It might not make sense to use Pair, in which case a specialized class similar to Pair could be used?

My current workaround is to change the key to org.gradle.unsafe.configuration-cache.enabled before deserializing.

[mgroth0]

Maybe a better solution might look like:

@Serializable
data class ConfigCacheProps(
    @PropertyValue
    val enabled: Boolean,
    val `max-problems`: Int
)

Where @PropertyValue is a new annotation that would indicate to serialize and deserialize according to the prefix for the object and exclude the name of the property (exclude ".enabled", making the associate key "org.gradle.unsafe.configuration-cache" and not "org.gradle.unsafe.configuration-cache.enabled"). There could only be one @PropertyValue per class. Similar to @pdvrieze 's nl.adaptivity.xmlutil.serialization.XmlValue