Two different classes used for type Page

[erDuo10]

interface org.springframework.data.domain.Page:
| return type of method public org.springframework.data.domain.Page com.erduo.FirstGraphql.resolver.Query.findAllAuthors(java.lang.Integer,java.lang.Integer)
| return type of method public org.springframework.data.domain.Page com.erduo.FirstGraphql.resolver.Query.findAllMyAuthors(java.lang.Integer,java.lang.Integer)

interface org.springframework.data.domain.Page:
| return type of method public org.springframework.data.domain.Page com.erduo.FirstGraphql.resolver.Query.findAllBooks(java.lang.Integer,java.lang.Integer)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:640) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]
... 142 common frames omitted
Caused by: com.coxautodev.graphql.tools.SchemaClassScannerError: Two different classes used for type Page:

interface org.springframework.data.domain.Page:
| return type of method public org.springframework.data.domain.Page com.erduo.FirstGraphql.resolver.Query.findAllAuthors(java.lang.Integer,java.lang.Integer)
| return type of method public org.springframework.data.domain.Page com.erduo.FirstGraphql.resolver.Query.findAllMyAuthors(java.lang.Integer,java.lang.Integer)

interface org.springframework.data.domain.Page:
| return type of method public org.springframework.data.domain.Page com.erduo.FirstGraphql.resolver.Query.findAllBooks(java.lang.Integer,java.lang.Integer)
at com.coxautodev.graphql.tools.SchemaClassScanner.handleFoundType(SchemaClassScanner.kt:319) ~[graphql-java-tools-5.7.1.jar:na]
at com.coxautodev.graphql.tools.SchemaClassScanner.handleFoundType(SchemaClassScanner.kt:293) ~[graphql-java-tools-5.7.1.jar:na]
at com.coxautodev.graphql.tools.SchemaClassScanner.scanResolverInfoForPotentialMatches(SchemaClassScanner.kt:268) ~[graphql-java-tools-5.7.1.jar:na]
at com.coxautodev.graphql.tools.SchemaClassScanner.handleRootType(SchemaClassScanner.kt:119) ~[graphql-java-tools-5.7.1.jar:na]
at com.coxautodev.graphql.tools.SchemaClassScanner.scanForClasses(SchemaClassScanner.kt:77) ~[graphql-java-tools-5.7.1.jar:na]
at com.coxautodev.graphql.tools.SchemaParserBuilder.scan(SchemaParserBuilder.kt:169) ~[graphql-java-tools-5.7.1.jar:na]
at com.coxautodev.graphql.tools.SchemaParserBuilder.build(SchemaParserBuilder.kt:210) ~[graphql-java-tools-5.7.1.jar:na]
at graphql.kickstart.tools.boot.GraphQLJavaToolsAutoConfiguration.schemaParser(GraphQLJavaToolsAutoConfiguration.java:115) ~[graphql-kickstart-spring-boot-autoconfigure-tools-6.0.0.jar:na]
at graphql.kickstart.tools.boot.GraphQLJavaToolsAutoConfiguration$$EnhancerBySpringCGLIB$$555cbf8c.CGLIB$schemaParser$1() ~[graphql-kickstart-spring-boot-autoconfigure-tools-6.0.0.jar:na]
at graphql.kickstart.tools.boot.GraphQLJavaToolsAutoConfiguration$$EnhancerBySpringCGLIB$$555cbf8c$$FastClassBySpringCGLIB$$16f0171.invoke() ~[graphql-kickstart-spring-boot-autoconfigure-tools-6.0.0.jar:na]
at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244) ~[spring-core-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:363) ~[spring-context-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at graphql.kickstart.tools.boot.GraphQLJavaToolsAutoConfiguration$$EnhancerBySpringCGLIB$$555cbf8c.schemaParser() ~[graphql-kickstart-spring-boot-autoconfigure-tools-6.0.0.jar:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_181]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_181]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_181]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_181]
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]
... 143 common frames omitted

java code

import org.springframework.data.domain.Page;

import com.coxautodev.graphql.tools.GraphQLQueryResolver;
import com.erduo.FirstGraphql.model.entity.business.Author;
import com.erduo.FirstGraphql.model.entity.business.Book;
import com.erduo.FirstGraphql.model.input.OffsetBasedPageRequest;
import com.erduo.FirstGraphql.service.AuthorService;
import com.erduo.FirstGraphql.service.BookService;

public class Query implements GraphQLQueryResolver {
private BookService bookService;
private AuthorService authorService;

public Query(AuthorService authorService, BookService bookService) {
	this.authorService = authorService;
	this.bookService = bookService;
}

public Page<Book> findAllBooks(Integer skip, Integer first) {		
	System.out.println("--------findAllBooks");
	return bookService.findAllBooks(new OffsetBasedPageRequest(skip.intValue(), first.intValue()));
}

public Page<Book> findAllMyBooks(Integer skip, Integer first) {
	System.out.println("--------findAllMyBooks");
	return bookService.findAllBooksByUser(new OffsetBasedPageRequest(skip.intValue(), first.intValue()));
}

public Page<Author> findAllAuthors(Integer skip, Integer first) {
	System.out.println("--------findAllAuthors");
	return authorService.findAllAuthors(new OffsetBasedPageRequest(skip.intValue(), first.intValue()));
}

public Page<Author> findAllMyAuthors(Integer skip, Integer first) {
	System.out.println("--------findAllMyAuthors");
	return authorService.findAllAuthorsByUser(new OffsetBasedPageRequest(skip.intValue(), first.intValue()));
}

public long countAllBooks() {
	return bookService.countAllBooks();
}

public long countAllMyBooks() {
	return bookService.countAllBooksByUser();
}

public long countAllAuthors() {
	return authorService.countAllAuthors();
}

public long countAllMyAuthors() {
	return authorService.countAllAuthorsByUser();
}
}

schema code

union SearchResult = Book | Author

type Page {
number: Int
size: Int
totalPages: Int
totalElements: Int
content: [SearchResult]
}

type Book{
id: ID!
title: String!
isbn: String!
pageCount: Int
author: Author
}

input CreateBookInput {
title: String!
isbn: String!
pageCount: Int
author: ID!
}

extend type Query {
findAllBooks(skip: Int = 0, first: Int = 0) : Page!
findAllMyBooks(skip: Int = 0, first: Int = 0) : Page!
countAllBooks: Long!
countAllMyBooks: Long!
}

extend type Mutation {
newBook(input:CreateBookInput!) : Book!
deleteBook(id: ID!) : Boolean
updateBookPageCount(pageCount: Int!, id: ID!) : Book!
}

type Author {
id: ID!
firstName: String!
lastName: String!
}

input CreateAuthorInput {
firstName: String!
lastName: String!
}

type Query {
findAllAuthors(skip: Int = 0, first: Int = 0) : Page!
findAllMyAuthors(skip: Int = 0, first: Int = 0) : Page!
countAllAuthors: Long!
countAllMyAuthors: Long!
}

type Mutation {
newAuthor(input: CreateAuthorInput!) : Author!
}