[backend] docs(queryable): add javadoc on queryable annotation (#1)

openaev-model/src/main/java/io/openaev/annotation/Queryable.java

@@ -6,31 +6,77 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+/**
+ * Annotation used to describe whether a JPA bean property can be searched, filtered, sorted or
+ * dynamically resolved by the query engine.
+ *
+ * <p>This annotation provides metadata to drive the construction of dynamic Spring Specifications
+ * and to expose query capabilities to higher-level components (API, UI, query builders, etc.).
+ *
+ * <p>It can be applied to fields or getter methods.
+ */
 @Retention(RetentionPolicy.RUNTIME)
 @Target({ElementType.FIELD, ElementType.METHOD})
 public @interface Queryable {
+
+  /**
+   * Enables free-text search on this property (e.g. using LIKE/ILIKE operators depending on the
+   * backend).
+   */
   boolean searchable() default false;
 
+  /** Allows filtering this property using supported filter operators. */
   boolean filterable() default false;
 
+  /**
+   * Indicates that the property refers to another entity stored in the database, meaning its
+   * possible filter values must be retrieved dynamically. Typically used for relations (ManyToOne,
+   * OneToMany, etc.).
+   */
   boolean dynamicValues() default false;
 
+  /** Allows sorting results based on this property. */
   boolean sortable() default false;
 
+  /** Human-readable label used for documentation or UI generation. */
   String label() default "";
 
+  /**
+   * Defines the JPA path used to query this property. Follows Spring Data Specification conventions
+   * (e.g. {@code "organization.id"}). Path should end by a primitive value or this can lead to
+   * UnsupportedOperationException.
+   */
   String path() default "";
 
+  /**
+   * Defines multiple possible JPA paths, when the property can be resolved through different
+   * relationships or aliases.
+   */
   String[] paths() default {};
 
+  /**
+   * Defines the complete list of operators available for filtering a collection by the decorated
+   * property. If undefined, the client is responsible for guessing which operators are applicable
+   * according to the decorated property type.
+   */
   Filters.FilterOperator[] overrideOperators() default {};
 
+  /**
+   * Define a value here to specify a type hint for clients to treat the decorated property as this
+   * type. Example: String[].class; clients parsing this hint will be encouraged to treat the value
+   * of the decorated property as an array of strings.
+   */
   Class clazz() default Unassigned.class;
 
+  /** Defines the Enum source for the allowed values of the decorated property, if applicable. */
   Class refEnumClazz() default Unassigned.class;
 
-  // use this absolutely specific class as a "null" value for class, refEnumClazz
-  // don't use Void here because that is a legitimate return type
-  // although there is little to justify having a queryable void method
+  /**
+   * Special sentinel class used to represent an "unassigned" state for {@link #clazz()} and {@link
+   * #refEnumClazz()}.
+   *
+   * <p>We cannot use {@code Void.class} here since {@code void} is a valid type and could lead to
+   * ambiguity.
+   */
   class Unassigned {}
 }