Add Nullable annotation to parameter of overridden equals method.

Closes #1374
Original pull request #1375

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/convert/Identifier.java

@@ -208,7 +208,7 @@ public final class Identifier {
 		}
 
 		@Override
-		public boolean equals(Object o) {
+		public boolean equals(@Nullable Object o) {
 
 			if (this == o)
 				return true;
@@ -272,7 +272,7 @@ public final class Identifier {
 	}
 
 	@Override
-	public boolean equals(Object o) {
+	public boolean equals(@Nullable Object o) {
 
 		if (this == o) return true;
 		if (o == null || getClass() != o.getClass()) return false;

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/convert/InsertSubject.java

@@ -17,6 +17,8 @@ package org.springframework.data.jdbc.core.convert;
 
 import java.util.Objects;
 
+import org.springframework.lang.Nullable;
+
 /**
  * The subject of an insert, described by the entity instance and its {@link Identifier}, where identifier contains
  * information about data that needs to be considered for the insert but which is not part of the entity. Namely
@@ -50,7 +52,7 @@ public final class InsertSubject<T> {
 	}
 
 	@Override
-	public boolean equals(Object o) {
+	public boolean equals(@Nullable Object o) {
 
 		if (this == o)
 			return true;

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/convert/SqlGenerator.java

@@ -1001,7 +1001,7 @@ class SqlGenerator {
 		}
 
 		@Override
-		public boolean equals(Object o) {
+		public boolean equals(@Nullable Object o) {
 
 			if (this == o) {
 				return true;

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/mapping/AggregateReference.java

@@ -65,7 +65,7 @@ public interface AggregateReference<T, ID> {
 		}
 
 		@Override
-		public boolean equals(Object o) {
+		public boolean equals(@Nullable Object o) {
 
 			if (this == o)
 				return true;

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/mapping/JdbcValue.java

@@ -55,7 +55,7 @@ public class JdbcValue {
 	}
 
 	@Override
-	public boolean equals(Object o) {
+	public boolean equals(@Nullable Object o) {
 
 		if (this == o)
 			return true;

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/repository/query/JdbcQueryCreator.java

@@ -352,7 +352,7 @@ class JdbcQueryCreator extends RelationalQueryCreator<ParametrizedQuery> {
 		}
 
 		@Override
-		public boolean equals(Object o) {
+		public boolean equals(@Nullable Object o) {
 
 			if (this == o)
 				return true;

spring-data-r2dbc/src/main/java/org/springframework/data/r2dbc/core/NamedParameterUtils.java

@@ -382,7 +382,7 @@ abstract class NamedParameterUtils {
 		}
 
 		@Override
-		public boolean equals(Object o) {
+		public boolean equals(@Nullable Object o) {
 			if (this == o)
 				return true;
 			if (!(o instanceof ParameterHolder))

spring-data-r2dbc/src/main/java/org/springframework/data/r2dbc/mapping/OutboundRow.java

@@ -24,6 +24,7 @@ import java.util.Set;
 import java.util.function.BiConsumer;
 
 import org.springframework.data.relational.core.sql.SqlIdentifier;
+import org.springframework.lang.Nullable;
 import org.springframework.r2dbc.core.Parameter;
 import org.springframework.util.Assert;
 
@@ -195,7 +196,7 @@ public class OutboundRow implements Map<SqlIdentifier, Parameter>, Cloneable {
 	}
 
 	@Override
-	public boolean equals(final Object o) {
+	public boolean equals(@Nullable final Object o) {
 
 		if (this == o) {
 			return true;

spring-data-r2dbc/src/test/java/org/springframework/data/r2dbc/repository/AbstractR2dbcRepositoryWithMixedCaseNamesIntegrationTests.java

@@ -142,7 +142,7 @@ public abstract class AbstractR2dbcRepositoryWithMixedCaseNamesIntegrationTests
 		}
 
 		@Override
-		public boolean equals(Object o) {
+		public boolean equals(@Nullable Object o) {
 			if (this == o)
 				return true;
 			if (o == null || getClass() != o.getClass())

spring-data-relational/src/main/java/org/springframework/data/relational/core/mapping/DerivedSqlIdentifier.java

@@ -21,6 +21,7 @@ import java.util.function.UnaryOperator;
 
 import org.springframework.data.relational.core.sql.IdentifierProcessing;
 import org.springframework.data.relational.core.sql.SqlIdentifier;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -69,7 +70,7 @@ class DerivedSqlIdentifier implements SqlIdentifier {
 	}
 
 	@Override
-	public boolean equals(Object o) {
+	public boolean equals(@Nullable Object o) {
 
 		if (this == o) {
 			return true;

spring-data-relational/src/main/java/org/springframework/data/relational/core/mapping/PersistentPropertyPathExtension.java

@@ -486,7 +486,7 @@ public class PersistentPropertyPathExtension {
 	}
 
 	@Override
-	public boolean equals(Object o) {
+	public boolean equals(@Nullable Object o) {
 
 		if (this == o)
 			return true;

spring-data-relational/src/main/java/org/springframework/data/relational/core/mapping/event/Identifier.java

@@ -17,6 +17,7 @@ package org.springframework.data.relational.core.mapping.event;
 
 import java.util.Objects;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -56,7 +57,7 @@ public final class Identifier {
 	}
 
 	@Override
-	public boolean equals(Object o) {
+	public boolean equals(@Nullable Object o) {
 
 		if (this == o)
 			return true;

spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/AbstractSegment.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.relational.core.sql;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
@@ -50,7 +51,7 @@ abstract class AbstractSegment implements Segment {
 	}
 
 	@Override
-	public boolean equals(Object obj) {
+	public boolean equals(@Nullable Object obj) {
 		return obj instanceof Segment && toString().equals(obj.toString());
 	}
 

spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/Column.java

@@ -360,7 +360,7 @@ public class Column extends AbstractSegment implements Expression, Named {
 	}
 
 	@Override
-	public boolean equals(Object o) {
+	public boolean equals(@Nullable Object o) {
 
 		if (this == o) {
 			return true;
@@ -421,7 +421,7 @@ public class Column extends AbstractSegment implements Expression, Named {
 		}
 
 		@Override
-		public boolean equals(Object o) {
+		public boolean equals(@Nullable Object o) {
 
 			if (this == o) {
 				return true;

spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/CompositeSqlIdentifier.java

@@ -20,6 +20,7 @@ import java.util.Iterator;
 import java.util.StringJoiner;
 import java.util.function.UnaryOperator;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -70,7 +71,7 @@ class CompositeSqlIdentifier implements SqlIdentifier {
 	}
 
 	@Override
-	public boolean equals(Object o) {
+	public boolean equals(@Nullable Object o) {
 
 		if (this == o) {
 			return true;

spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/DefaultSqlIdentifier.java

@@ -19,6 +19,7 @@ import java.util.Collections;
 import java.util.Iterator;
 import java.util.function.UnaryOperator;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -65,7 +66,7 @@ class DefaultSqlIdentifier implements SqlIdentifier {
 	}
 
 	@Override
-	public boolean equals(Object o) {
+	public boolean equals(@Nullable Object o) {
 
 		if (this == o) {
 			return true;

spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/Table.java

@@ -17,6 +17,7 @@ package org.springframework.data.relational.core.sql;
 
 import java.util.Objects;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -131,7 +132,7 @@ public class Table extends AbstractSegment implements TableLike {
 	}
 
 	@Override
-	public boolean equals(Object o) {
+	public boolean equals(@Nullable Object o) {
 		if (this == o) {
 			return true;
 		}
@@ -189,7 +190,7 @@ public class Table extends AbstractSegment implements TableLike {
 		}
 
 		@Override
-		public boolean equals(Object o) {
+		public boolean equals(@Nullable Object o) {
 
 			if (this == o) {
 				return true;