#115 - Mapping - Add support for @ElementCollection enhancement

Initial support - simple List.

src/main/java/io/ebeaninternal/server/query/STreePropertyAssocOne.java

@@ -0,0 +1,16 @@
+package io.ebeaninternal.server.query;
+
+import io.ebeaninternal.server.type.ScalarType;
+
+public interface STreePropertyAssocOne extends STreePropertyAssoc {
+
+  /**
+   * Return true if the property is an Id.
+   */
+  boolean isAssocId();
+
+  /**
+   * Return the scalar type of the associated id property.
+   */
+  ScalarType<?> getIdScalarType();
+}