Improve multiversion support

src/main/java/ca/uhn/fhir/jpa/starter/FhirServerConfigR4.java

@@ -0,0 +1,57 @@
+package ca.uhn.fhir.jpa.starter;
+
+import ca.uhn.fhir.context.ConfigurationException;
+import ca.uhn.fhir.jpa.config.BaseJavaConfigR4;
+import ca.uhn.fhir.jpa.search.DatabaseBackedPagingProvider;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.orm.jpa.JpaTransactionManager;
+import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
+
+import javax.persistence.EntityManagerFactory;
+import javax.sql.DataSource;
+
+@Configuration
+public class FhirServerConfigR4 extends BaseJavaConfigR4 {
+
+    @Autowired
+    private DataSource myDataSource;
+
+    /**
+     * We override the paging provider definition so that we can customize
+     * the default/max page sizes for search results. You can set these however
+     * you want, although very large page sizes will require a lot of RAM.
+     */
+    @Override
+    public DatabaseBackedPagingProvider databaseBackedPagingProvider() {
+        DatabaseBackedPagingProvider pagingProvider = super.databaseBackedPagingProvider();
+        pagingProvider.setDefaultPageSize(HapiProperties.getDefaultPageSize());
+        pagingProvider.setMaximumPageSize(HapiProperties.getMaximumPageSize());
+        return pagingProvider;
+    }
+
+    @Override
+    @Bean()
+    public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
+        LocalContainerEntityManagerFactoryBean retVal = super.entityManagerFactory();
+        retVal.setPersistenceUnitName(HapiProperties.getPersistenceUnitName());
+
+        try {
+            retVal.setDataSource(myDataSource);
+        } catch (Exception e) {
+            throw new ConfigurationException("Could not set the data source due to a configuration issue", e);
+        }
+
+        retVal.setJpaProperties(HapiProperties.getProperties());
+        return retVal;
+    }
+
+    @Bean()
+    public JpaTransactionManager transactionManager(EntityManagerFactory entityManagerFactory) {
+        JpaTransactionManager retVal = new JpaTransactionManager();
+        retVal.setEntityManagerFactory(entityManagerFactory);
+        return retVal;
+    }
+
+}