[SIS-567] Resolve serialization compiler warnings

• Type: Task
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 1.0, 1.1, 1.2, 1.3
• Fix Version/s: 1.4
• Component/s: Metadata, Referencing, Storage, Utilities
• Assignee: Martin Desruisseaux
• Reporter: Martin Desruisseaux
• Created: 02/Jan/23 11:28
• Updated: 15/Jan/23 10:07
• Resolved: 15/Jan/23 10:07

Description

Since Java 18, the compiler emit the following warnings on many fields, especially in metadata and referencing modules:

Non-transient instance field of a serializable class declared with a non-serializable type.

In a lot of cases, the field type is an interface where all implementations used in practice are serializable. We resolve those warnings with the following annotation:

@SuppressWarnings("serial")         // Most SIS implementations are serializable.

In a few cases the value can be anything (e.g. type of values in a collection). We use the following annotation for them.

@SuppressWarnings("serial")         // Not statically typed as Serializable.

Finally there is a few classes where we could not yet resolve the warning:

• org.apache.sis.internal.util.StandardDateFormat has a java.time.format.DateTimeFormatter field, which is not serializable.
• org.apache.sis.internal.referencing.provider.DatumShiftGridFile has a java.nio.file.Path field.
• org.apache.sis.gui.dataset.ResourceEvent has a java.nio.file.Path field.

For the later two, maybe Path could be replaced by URI.

Issue Links

• depends upon: SIS-569 Replace Path by URI for datum shift grid files