Prefer explicitly declared generic parameter over Iterable in TypeDiscoverer.getComponentType().

Related ticket: #2312.

Author: odrotbohm

Diff for: src/main/java/org/springframework/data/util/TypeDiscoverer.java

@@ -148,6 +148,12 @@ protected TypeInformation<?> doGetComponentType() {
 			return getTypeArgument(CustomCollections.getMapBaseType(rawType), 0);
 		}
 
+		List<TypeInformation<?>> arguments = getTypeArguments();
+
+		if (arguments.size() > 0) {
+			return arguments.get(0);
+		}
+
 		if (Iterable.class.isAssignableFrom(rawType)) {
 			return getTypeArgument(Iterable.class, 0);
 		}
@@ -156,9 +162,7 @@ protected TypeInformation<?> doGetComponentType() {
 			return getTypeArgument(rawType, 0);
 		}
 
-		List<TypeInformation<?>> arguments = getTypeArguments();
-
-		return arguments.size() > 0 ? arguments.get(0) : null;
+		return null;
 	}
 
 	@Override

Diff for: src/test/java/org/springframework/data/util/TypeDiscovererUnitTests.java

@@ -31,6 +31,7 @@
 import org.mockito.junit.jupiter.MockitoExtension;
 import org.springframework.beans.factory.annotation.Autowire;
 import org.springframework.core.ResolvableType;
+import org.springframework.data.geo.GeoResults;
 import org.springframework.util.ReflectionUtils;
 
 /**
@@ -326,6 +327,14 @@ void detectsMapKeyAndValueOnEnumMaps() {
 		assertThat(map.getMapValueType().getType()).isEqualTo(String.class);
 	}
 
+	@Test
+	void detectsComponentTypeOfTypedClass() {
+
+		TypeInformation<?> property = TypeInformation.of(GeoResultsWrapper.class).getProperty("results");
+
+		assertThat(property.getComponentType().getType()).isEqualTo(Leaf.class);
+	}
+
 	class Person {
 
 		Addresses addresses;
@@ -415,4 +424,8 @@ class Leaf {}
 	class EnumMapWrapper {
 		EnumMap<Autowire, String> map;
 	}
+
+	class GeoResultsWrapper {
+		GeoResults<Leaf> results;
+	}
 }