DATACMNS-1556 - General performance improvements in repository execution.

We now avoid the allocation of an Optional instance in the lookup of a dynamic projection in ParameterAccessor. Also, Lazy now exposes a ….getNullable() to be favored over ….getOptional() for hot code paths.

Replaced Stream and Optional usage with for-loops and nullable return values. Reuse parameter names to avoid repeated annotation lookups. Reuse result from Parameters.getBindable(). Introduce ParametersParameterAccessor.getValues() to consistently reuse a single accessor instance allowing access to the unwrapped values. Introduce type cache to QueryExecutionConverters to quickly reject types that do not require wrapping. Avoid recalculation of QueryMethod.isCollectionQuery().

src/main/java/org/springframework/data/util/Lazy.java

@@ -74,7 +74,7 @@ public class Lazy<T> implements Supplier<T> {
 
 	/**
 	 * Creates a pre-resolved empty {@link Lazy}.
-	 * 
+	 *
 	 * @return
 	 * @since 2.1
 	 */
@@ -103,7 +103,7 @@ public class Lazy<T> implements Supplier<T> {
 	/**
 	 * Returns the {@link Optional} value created by the configured {@link Supplier}, allowing the absence of values in
 	 * contrast to {@link #get()}. Will return the calculated instance for subsequent lookups.
-	 * 
+	 *
 	 * @return
 	 */
 	public Optional<T> getOptional() {
@@ -112,7 +112,7 @@ public class Lazy<T> implements Supplier<T> {
 
 	/**
 	 * Returns a new Lazy that will consume the given supplier in case the current one does not yield in a result.
-	 * 
+	 *
 	 * @param supplier must not be {@literal null}.
 	 * @return
 	 */
@@ -125,7 +125,7 @@ public class Lazy<T> implements Supplier<T> {
 
 	/**
 	 * Returns a new Lazy that will return the given value in case the current one does not yield in a result.
-	 * 
+	 *
 	 * @param supplier must not be {@literal null}.
 	 * @return
 	 */
@@ -198,9 +198,10 @@ public class Lazy<T> implements Supplier<T> {
 	 * Returns the value of the lazy evaluation.
 	 *
 	 * @return
+	 * @since 2.2
 	 */
 	@Nullable
-	private T getNullable() {
+	public T getNullable() {
 
 		T value = this.value;