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Why is Kotlin keeping MetaData in Kotlin class file?

We converted the Java file to a Kotlin file and then compiled it into a class file. The resulting class is larger than the original Java class file. In the Kotlin class file, we found metadata in each class. Why does Kotlin store this metadata?

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Certain aspects of Kotlin code cannot be expressed in pure Java bytecode (e.g. nullability, primary constructors, internal

visibility, modifier lateinit

, property delegation, etc.). Instead, they are serialized and stored as metadata in the classes.

When you use a JAR distribution of a Kotlin library, the compiler parses the metadata to discover these specific Kotlin attributes in order to use the library as a Kotlin artifact with all the available functionality.



At runtime, the metadata is used by the kotlin-reflect

Kotlin reflection API to restore these attributes and make them available through reflection.

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