Fixed incorrect docs PersistentPropertyPath and optimized sublist

src/main/java/org/springframework/data/mapping/PersistentPropertyPath.java

@@ -29,8 +29,6 @@ public interface PersistentPropertyPath<P extends PersistentProperty<P>> extends
 
 	/**
 	 * Returns the dot based path notation using {@link PersistentProperty#getName()}.
-	 *
-	 * @return
 	 */
 	@Nullable
 	String toDotPath();
@@ -40,7 +38,6 @@ public interface PersistentPropertyPath<P extends PersistentProperty<P>> extends
 	 * {@link PersistentProperty}s to path segments.
 	 *
 	 * @param converter must not be {@literal null}.
-	 * @return
 	 */
 	@Nullable
 	String toDotPath(Converter<? super P, String> converter);
@@ -49,7 +46,6 @@ public interface PersistentPropertyPath<P extends PersistentProperty<P>> extends
 	 * Returns a {@link String} path with the given delimiter based on the {@link PersistentProperty#getName()}.
 	 *
 	 * @param delimiter must not be {@literal null}.
-	 * @return
 	 */
 	@Nullable
 	String toPath(String delimiter);
@@ -60,7 +56,6 @@ public interface PersistentPropertyPath<P extends PersistentProperty<P>> extends
 	 *
 	 * @param delimiter must not be {@literal null}.
 	 * @param converter must not be {@literal null}.
-	 * @return
 	 */
 	@Nullable
 	String toPath(String delimiter, Converter<? super P, String> converter);
@@ -70,7 +65,6 @@ public interface PersistentPropertyPath<P extends PersistentProperty<P>> extends
 	 * {@link PersistentProperty} for {@code bar}. For a simple {@code foo} it returns {@link PersistentProperty} for
 	 * {@code foo}.
 	 *
-	 * @return
 	 */
 	@Nullable
 	P getLeafProperty();
@@ -90,44 +84,36 @@ default P getRequiredLeafProperty() {
 	 * Returns the first property in the {@link PersistentPropertyPath}. So for {@code foo.bar} it will return the
 	 * {@link PersistentProperty} for {@code foo}. For a simple {@code foo} it returns {@link PersistentProperty} for
 	 * {@code foo}.
-	 *
-	 * @return
 	 */
 	@Nullable
 	P getBaseProperty();
 
 	/**
 	 * Returns whether the given {@link PersistentPropertyPath} is a base path of the current one. This means that the
-	 * current {@link PersistentPropertyPath} is basically an extension of the given one.
+	 * given {@link PersistentPropertyPath} is basically an extension of this {@link PersistentPropertyPath}.
 	 *
 	 * @param path must not be {@literal null}.
-	 * @return
 	 */
 	boolean isBasePathOf(PersistentPropertyPath<P> path);
 
 	/**
 	 * Returns the sub-path of the current one as if it was based on the given base path. So for a current path
 	 * {@code foo.bar} and a given base {@code foo} it would return {@code bar}. If the given path is not a base of the
-	 * the current one the current {@link PersistentPropertyPath} will be returned as is.
+	 * current one the current {@link PersistentPropertyPath} will be returned as is.
 	 *
 	 * @param base must not be {@literal null}.
-	 * @return
 	 */
 	PersistentPropertyPath<P> getExtensionForBaseOf(PersistentPropertyPath<P> base);
 
 	/**
 	 * Returns the parent path of the current {@link PersistentPropertyPath}, i.e. the path without the leaf property.
 	 * This happens up to the base property. So for a direct property reference calling this method will result in
 	 * returning the property.
-	 *
-	 * @return
 	 */
 	PersistentPropertyPath<P> getParentPath();
 
 	/**
 	 * Returns the length of the {@link PersistentPropertyPath}.
-	 *
-	 * @return
 	 */
 	int getLength();
 }

src/main/java/org/springframework/data/mapping/context/DefaultPersistentPropertyPath.java

@@ -38,7 +38,7 @@
  */
 class DefaultPersistentPropertyPath<P extends PersistentProperty<P>> implements PersistentPropertyPath<P> {
 
-	private static final Converter<PersistentProperty<?>, String> DEFAULT_CONVERTER = (source) -> source.getName();
+	private static final Converter<PersistentProperty<?>, String> DEFAULT_CONVERTER = PersistentProperty::getName;
 	private static final String DEFAULT_DELIMITER = ".";
 
 	private final List<P> properties;
@@ -131,25 +131,43 @@ public P getBaseProperty() {
 	}
 
 	public boolean isBasePathOf(PersistentPropertyPath<P> path) {
+		return this.equals(getCommonBaseWith(path));
+	}
 
-		Assert.notNull(path, "PersistentPropertyPath must not be null");
+	/**
+	 * Return the common base path that this {@link PersistentPropertyPath} has with passed {@link PersistentPropertyPath}
+	 *
+	 * That is, for example, if this {@link PersistentPropertyPath} equals to one.two.three, and passed {@link PersistentPropertyPath}
+	 * is equals to one.two.four, that the return will be the {@link PersistentPropertyPath} containing one.two properties
+	 */
+	public PersistentPropertyPath<P> getCommonBaseWith(PersistentPropertyPath<P> anotherPath) {
+
+		Assert.notNull(anotherPath, "PersistentPropertyPath must not be null");
+
+		if (anotherPath.isEmpty()) {
+			return DefaultPersistentPropertyPath.empty();
+		}
 
-		Iterator<P> iterator = path.iterator();
+		List<P> commonPart = new ArrayList<>();
 
-		for (P property : this) {
+		Iterator<P> iterator = anotherPath.iterator();
+
+		for (P property: this) {
 
 			if (!iterator.hasNext()) {
-				return false;
+				break;
 			}
 
-			P reference = iterator.next();
+			P next = iterator.next();
 
-			if (!property.equals(reference)) {
-				return false;
+			if (property.equals(next)) {
+				commonPart.add(property);
+			} else {
+				break;
 			}
 		}
 
-		return true;
+		return new DefaultPersistentPropertyPath<>(commonPart);
 	}
 
 	public PersistentPropertyPath<P> getExtensionForBaseOf(PersistentPropertyPath<P> base) {
@@ -158,18 +176,7 @@ public PersistentPropertyPath<P> getExtensionForBaseOf(PersistentPropertyPath<P>
 			return this;
 		}
 
-		List<P> result = new ArrayList<>();
-		Iterator<P> iterator = iterator();
-
-		for (int i = 0; i < base.getLength(); i++) {
-			iterator.next();
-		}
-
-		while (iterator.hasNext()) {
-			result.add(iterator.next());
-		}
-
-		return new DefaultPersistentPropertyPath<>(result);
+		return new DefaultPersistentPropertyPath<>(properties.subList(base.getLength(), properties.size()));
 	}
 
 	public PersistentPropertyPath<P> getParentPath() {

src/test/java/org/springframework/data/mapping/context/DefaultPersistentPropertyPathUnitTests.java

@@ -21,6 +21,7 @@
 
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.List;
 
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -40,7 +41,7 @@
 @ExtendWith(MockitoExtension.class)
 class DefaultPersistentPropertyPathUnitTests<P extends PersistentProperty<P>> {
 
-	@Mock P first, second;
+	@Mock P first, second, third;
 
 	@Mock Converter<P, String> converter;
 
@@ -58,6 +59,65 @@ void rejectsNullProperties() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new DefaultPersistentPropertyPath<>(null));
 	}
 
+	@Test
+	void getCommonBaseTestEmpty() {
+		DefaultPersistentPropertyPath<P> propertyPath = new DefaultPersistentPropertyPath<>(List.of(first, second));
+
+		assertThat(propertyPath.getCommonBaseWith(DefaultPersistentPropertyPath.empty())).isEmpty();
+	}
+
+	@Test
+	void getCommonBaseTestNoCommonBase() {
+		DefaultPersistentPropertyPath<P> propertyPath = new DefaultPersistentPropertyPath<>(List.of(first));
+
+		assertThat(propertyPath.getCommonBaseWith(new DefaultPersistentPropertyPath<>(List.of(second)))).isEmpty();
+	}
+
+	@Test
+	void getCommonBaseTestCommonBasePresentInPassed() {
+		DefaultPersistentPropertyPath<P> propertyPath = new DefaultPersistentPropertyPath<>(List.of(first));
+
+		assertThat(propertyPath.getCommonBaseWith(new DefaultPersistentPropertyPath<>(List.of(first, second)))).isEqualTo(propertyPath);
+	}
+
+	@Test
+	void getCommonBaseTestCommonBasePresentInThis() {
+		DefaultPersistentPropertyPath<P> propertyPath = new DefaultPersistentPropertyPath<>(List.of(first, second));
+
+		DefaultPersistentPropertyPath<P> anotherPath = new DefaultPersistentPropertyPath<>(List.of(first));
+
+		assertThat(propertyPath.getCommonBaseWith(anotherPath)).isEqualTo(anotherPath);
+	}
+
+	@Test
+	void getCommonBaseTestTheSamePath() {
+		DefaultPersistentPropertyPath<P> propertyPath = new DefaultPersistentPropertyPath<>(List.of(first, second));
+
+		DefaultPersistentPropertyPath<P> anotherPath = new DefaultPersistentPropertyPath<>(List.of(first, second));
+
+		assertThat(propertyPath.getCommonBaseWith(anotherPath)).isEqualTo(anotherPath);
+	}
+
+	@Test
+	void getCommonBaseTestHasSamePropertiesInDifferentOrder() {
+		DefaultPersistentPropertyPath<P> propertyPath = new DefaultPersistentPropertyPath<>(List.of(first, second));
+
+		DefaultPersistentPropertyPath<P> anotherPath = new DefaultPersistentPropertyPath<>(List.of(second, first));
+
+		assertThat(propertyPath.getCommonBaseWith(anotherPath)).isEqualTo(DefaultPersistentPropertyPath.empty());
+	}
+
+
+	@Test
+	void getCommonBaseTestHasSamePropertiesButNotInBase() {
+		DefaultPersistentPropertyPath<P> propertyPath = new DefaultPersistentPropertyPath<>(List.of(first, second));
+
+		DefaultPersistentPropertyPath<P> anotherPath = new DefaultPersistentPropertyPath<>(List.of(third, second));
+
+		assertThat(propertyPath.getCommonBaseWith(anotherPath)).isEqualTo(DefaultPersistentPropertyPath.empty());
+	}
+
+
 	@Test
 	void usesPropertyNameForSimpleDotPath() {