Stack Exchange
Spring Boot Ambiguous mapping. Cannot map method
I have 2 REST controllers in my Spring Boot application with simple CRUD operations.
REST controller, that is mapped to "/json/currency"
package ua.alekstar.moneysaver.rest;

import org.springframework.web.bind.annotation.*;
import ua.alekstar.moneysaver.rest.currency.Currencies;
import ua.alekstar.moneysaver.rest.currency.Currency;
import ua.alekstar.moneysaver.service.CurrencyService;

import java.util.Collections;

@RestController("/json/currency")
public class CurrencyJsonRestController {

    private final CurrencyService currencyService;

    public CurrencyJsonRestController(CurrencyService currencyService) {
        this.currencyService = currencyService;
    }

    @GetMapping
    @ResponseBody
    public Currencies get(@RequestParam(required = false) Long id) {
        if (id == null) {
            return readAll();
        }
        return read(id);
    }

    private Currencies read(Long id) {
        return new Currencies(Collections.singletonList(currencyService.read(id)));
    }

    private Currencies readAll() {
        return new Currencies(currencyService.readAll());
    }

    @PostMapping
    public void post(@RequestBody Currency currency) {
        currencyService.create(currency.toEntity());
    }

    @PutMapping
    public void put(@RequestBody Currency currency) {
        currencyService.update(currency.toEntity());
    }

    @DeleteMapping
    public void delete(@RequestParam Long id) {
        currencyService.delete(id);
    }
}

and REST controller, that is mapped to "/json/account"
package ua.alekstar.moneysaver.rest;

import org.springframework.web.bind.annotation.*;
import ua.alekstar.moneysaver.dao.entities.Currency;
import ua.alekstar.moneysaver.rest.account.Account;
import ua.alekstar.moneysaver.rest.account.Accounts;
import ua.alekstar.moneysaver.service.AccountService;
import ua.alekstar.moneysaver.service.CurrencyService;

import java.util.Collections;

@RestController("/json/account")
public class AccountJsonRestController {

    private final AccountService accountService;
    private final CurrencyService currencyService;

    public AccountJsonRestController(AccountService accountService, CurrencyService currencyService) {
        this.accountService = accountService;
        this.currencyService = currencyService;
    }

    @GetMapping
    @ResponseBody
    public Accounts get(@RequestParam(required = false) Long id) {
        if (id == null) {
            return readAll();
        }
        return read(id);
    }

    private Accounts read(Long id) {
        return new Accounts(Collections.singletonList(accountService.read(id)));
    }

    private Accounts readAll() {
        return new Accounts(accountService.readAll());
    }

    @PostMapping
    public void post(@RequestBody Account account) {
        accountService.create(toEntity(account));
    }

    private ua.alekstar.moneysaver.dao.entities.Account toEntity(Account account) {
        final Currency currency = currencyService.readByIsoCode(account.getCurrency());
        return new ua.alekstar.moneysaver.dao.entities.Account(account.getId(), account.getName(), currency);
    }

    @PutMapping
    public void put(@RequestBody Account account) {
        accountService.update(toEntity(account));
    }

    @DeleteMapping
    public void delete(@RequestParam Long id) {
        accountService.delete(id);
    }

}

While I start my application I have an exception and I do not understand why it happens.
/usr/lib/jvm/java-8-oracle/bin/java -XX:TieredStopAtLevel=1 -noverify -Dspring.output.ansi.enabled=always -javaagent:/home/sasha/Applications/idea-IU-171.3780.107/lib/idea_rt.jar=32820:/home/sasha/Applications/idea-IU-171.3780.107/bin -Dfile.encoding=UTF-8 -classpath /usr/lib/jvm/java-8-oracle/jre/lib/charsets.jar:/usr/lib/jvm/java-8-oracle/jre/lib/deploy.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/cldrdata.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/dnsns.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/jaccess.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/jfxrt.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/localedata.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/nashorn.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/sunec.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/sunjce_provider.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/sunpkcs11.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/zipfs.jar:/usr/lib/jvm/java-8-oracle/jre/lib/javaws.jar:/usr/lib/jvm/java-8-oracle/jre/lib/jce.jar:/usr/lib/jvm/java-8-oracle/jre/lib/jfr.jar:/usr/lib/jvm/java-8-oracle/jre/lib/jfxswt.jar:/usr/lib/jvm/java-8-oracle/jre/lib/jsse.jar:/usr/lib/jvm/java-8-oracle/jre/lib/management-agent.jar:/usr/lib/jvm/java-8-oracle/jre/lib/plugin.jar:/usr/lib/jvm/java-8-oracle/jre/lib/resources.jar:/usr/lib/jvm/java-8-oracle/jre/lib/rt.jar:/home/sasha/Documents/development/moneysaver/target/classes:/home/sasha/.m2/repository/org/springframework/boot/spring-boot-starter-data-jpa/1.5.3.RELEASE/spring-boot-starter-data-jpa-1.5.3.RELEASE.jar:/home/sasha/.m2/repository/org/springframework/boot/spring-boot-starter/1.5.3.RELEASE/spring-boot-starter-1.5.3.RELEASE.jar:/home/sasha/.m2/repository/org/springframework/boot/spring-boot/1.5.3.RELEASE/spring-boot-1.5.3.RELEASE.jar:/home/sasha/.m2/repository/org/springframework/boot/spring-boot-autoconfigure/1.5.3.RELEASE/spring-boot-autoconfigure-1.5.3.RELEASE.jar:/home/sasha/.m2/repository/org/springframework/boot/spring-boot-starter-logging/1.5.3.RELEASE/spring-boot-starter-logging-1.5.3.RELEASE.jar:/home/sasha/.m2/repository/ch/qos/logback/logback-classic/1.1.11/logback-classic-1.1.11.jar:/home/sasha/.m2/repository/ch/qos/logback/logback-core/1.1.11/logback-core-1.1.11.jar:/home/sasha/.m2/repository/org/slf4j/jul-to-slf4j/1.7.25/jul-to-slf4j-1.7.25.jar:/home/sasha/.m2/repository/org/slf4j/log4j-over-slf4j/1.7.25/log4j-over-slf4j-1.7.25.jar:/home/sasha/.m2/repository/org/yaml/snakeyaml/1.17/snakeyaml-1.17.jar:/home/sasha/.m2/repository/org/springframework/boot/spring-boot-starter-aop/1.5.3.RELEASE/spring-boot-starter-aop-1.5.3.RELEASE.jar:/home/sasha/.m2/repository/org/springframework/spring-aop/4.3.8.RELEASE/spring-aop-4.3.8.RELEASE.jar:/home/sasha/.m2/repository/org/aspectj/aspectjweaver/1.8.10/aspectjweaver-1.8.10.jar:/home/sasha/.m2/repository/org/springframework/boot/spring-boot-starter-jdbc/1.5.3.RELEASE/spring-boot-starter-jdbc-1.5.3.RELEASE.jar:/home/sasha/.m2/repository/org/apache/tomcat/tomcat-jdbc/8.5.14/tomcat-jdbc-8.5.14.jar:/home/sasha/.m2/repository/org/apache/tomcat/tomcat-juli/8.5.14/tomcat-juli-8.5.14.jar:/home/sasha/.m2/repository/org/springframework/spring-jdbc/4.3.8.RELEASE/spring-jdbc-4.3.8.RELEASE.jar:/home/sasha/.m2/repository/javax/transaction/javax.transaction-api/1.2/javax.transaction-api-1.2.jar:/home/sasha/.m2/repository/org/springframework/data/spring-data-jpa/1.11.3.RELEASE/spring-data-jpa-1.11.3.RELEASE.jar:/home/sasha/.m2/repository/org/springframework/data/spring-data-commons/1.13.3.RELEASE/spring-data-commons-1.13.3.RELEASE.jar:/home/sasha/.m2/repository/org/springframework/spring-orm/4.3.8.RELEASE/spring-orm-4.3.8.RELEASE.jar:/home/sasha/.m2/repository/org/springframework/spring-context/4.3.8.RELEASE/spring-context-4.3.8.RELEASE.jar:/home/sasha/.m2/repository/org/springframework/spring-tx/4.3.8.RELEASE/spring-tx-4.3.8.RELEASE.jar:/home/sasha/.m2/repository/org/springframework/spring-beans/4.3.8.RELEASE/spring-beans-4.3.8.RELEASE.jar:/home/sasha/.m2/repository/org/slf4j/slf4j-api/1.7.25/slf4j-api-1.7.25.jar:/home/sasha/.m2/repository/org/slf4j/jcl-over-slf4j/1.7.25/jcl-over-slf4j-1.7.25.jar:/home/sasha/.m2/repository/org/springframework/spring-aspects/4.3.8.RELEASE/spring-aspects-4.3.8.RELEASE.jar:/home/sasha/.m2/repository/org/springframework/boot/spring-boot-starter-web/1.5.3.RELEASE/spring-boot-starter-web-1.5.3.RELEASE.jar:/home/sasha/.m2/repository/org/springframework/boot/spring-boot-starter-tomcat/1.5.3.RELEASE/spring-boot-starter-tomcat-1.5.3.RELEASE.jar:/home/sasha/.m2/repository/org/apache/tomcat/embed/tomcat-embed-core/8.5.14/tomcat-embed-core-8.5.14.jar:/home/sasha/.m2/repository/org/apache/tomcat/embed/tomcat-embed-el/8.5.14/tomcat-embed-el-8.5.14.jar:/home/sasha/.m2/repository/org/apache/tomcat/embed/tomcat-embed-websocket/8.5.14/tomcat-embed-websocket-8.5.14.jar:/home/sasha/.m2/repository/org/hibernate/hibernate-validator/5.3.5.Final/hibernate-validator-5.3.5.Final.jar:/home/sasha/.m2/repository/javax/validation/validation-api/1.1.0.Final/validation-api-1.1.0.Final.jar:/home/sasha/.m2/repository/com/fasterxml/jackson/core/jackson-databind/2.8.8/jackson-databind-2.8.8.jar:/home/sasha/.m2/repository/com/fasterxml/jackson/core/jackson-annotations/2.8.0/jackson-annotations-2.8.0.jar:/home/sasha/.m2/repository/com/fasterxml/jackson/core/jackson-core/2.8.8/jackson-core-2.8.8.jar:/home/sasha/.m2/repository/org/springframework/spring-web/4.3.8.RELEASE/spring-web-4.3.8.RELEASE.jar:/home/sasha/.m2/repository/org/springframework/spring-webmvc/4.3.8.RELEASE/spring-webmvc-4.3.8.RELEASE.jar:/home/sasha/.m2/repository/org/springframework/spring-expression/4.3.8.RELEASE/spring-expression-4.3.8.RELEASE.jar:/home/sasha/.m2/repository/org/springframework/spring-core/4.3.8.RELEASE/spring-core-4.3.8.RELEASE.jar:/home/sasha/.m2/repository/org/hibernate/javax/persistence/hibernate-jpa-2.0-api/1.0.1.Final/hibernate-jpa-2.0-api-1.0.1.Final.jar:/home/sasha/.m2/repository/org/hibernate/hibernate-core/5.2.10.Final/hibernate-core-5.2.10.Final.jar:/home/sasha/.m2/repository/org/jboss/logging/jboss-logging/3.3.1.Final/jboss-logging-3.3.1.Final.jar:/home/sasha/.m2/repository/org/hibernate/javax/persistence/hibernate-jpa-2.1-api/1.0.0.Final/hibernate-jpa-2.1-api-1.0.0.Final.jar:/home/sasha/.m2/repository/org/javassist/javassist/3.21.0-GA/javassist-3.21.0-GA.jar:/home/sasha/.m2/repository/antlr/antlr/2.7.7/antlr-2.7.7.jar:/home/sasha/.m2/repository/org/jboss/spec/javax/transaction/jboss-transaction-api_1.2_spec/1.0.1.Final/jboss-transaction-api_1.2_spec-1.0.1.Final.jar:/home/sasha/.m2/repository/org/jboss/jandex/2.0.3.Final/jandex-2.0.3.Final.jar:/home/sasha/.m2/repository/com/fasterxml/classmate/1.3.3/classmate-1.3.3.jar:/home/sasha/.m2/repository/dom4j/dom4j/1.6.1/dom4j-1.6.1.jar:/home/sasha/.m2/repository/org/hibernate/common/hibernate-commons-annotations/5.0.1.Final/hibernate-commons-annotations-5.0.1.Final.jar:/home/sasha/.m2/repository/org/hibernate/hibernate-entitymanager/5.2.10.Final/hibernate-entitymanager-5.2.10.Final.jar:/home/sasha/.m2/repository/net/bytebuddy/byte-buddy/1.6.6/byte-buddy-1.6.6.jar:/home/sasha/.m2/repository/org/hibernate/hibernate-ehcache/5.2.10.Final/hibernate-ehcache-5.2.10.Final.jar:/home/sasha/.m2/repository/net/sf/ehcache/ehcache/2.10.4/ehcache-2.10.4.jar:/home/sasha/.m2/repository/com/mchange/c3p0/0.9.5.2/c3p0-0.9.5.2.jar:/home/sasha/.m2/repository/com/mchange/mchange-commons-java/0.2.11/mchange-commons-java-0.2.11.jar:/home/sasha/.m2/repository/org/postgresql/postgresql/42.0.0/postgresql-42.0.0.jar ua.alekstar.moneysaver.MoneysaverApplication

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v1.5.3.RELEASE)

2017-05-13 21:15:20.109  INFO 9745 --- [           main] u.a.moneysaver.MoneysaverApplication     : Starting MoneysaverApplication on sasha-pc with PID 9745 (/home/sasha/Documents/development/moneysaver/target/classes started by sasha in /home/sasha/Documents/development/moneysaver)
2017-05-13 21:15:20.112  INFO 9745 --- [           main] u.a.moneysaver.MoneysaverApplication     : No active profile set, falling back to default profiles: default
2017-05-13 21:15:20.165  INFO 9745 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@319b92f3: startup date [Sat May 13 21:15:20 EEST 2017]; root of context hierarchy
2017-05-13 21:15:22.043  INFO 9745 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http)
2017-05-13 21:15:22.053  INFO 9745 --- [           main] o.apache.catalina.core.StandardService   : Starting service Tomcat
2017-05-13 21:15:22.054  INFO 9745 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.14
2017-05-13 21:15:22.147  INFO 9745 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2017-05-13 21:15:22.147  INFO 9745 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 1985 ms
2017-05-13 21:15:22.259  INFO 9745 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Mapping servlet: 'dispatcherServlet' to [/]
2017-05-13 21:15:22.262  INFO 9745 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
2017-05-13 21:15:22.263  INFO 9745 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2017-05-13 21:15:22.263  INFO 9745 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2017-05-13 21:15:22.263  INFO 9745 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
2017-05-13 21:15:22.311  INFO 9745 --- [g-Init-Reporter] com.mchange.v2.log.MLog                  : MLog clients using slf4j logging.
2017-05-13 21:15:22.394  INFO 9745 --- [           main] j.LocalContainerEntityManagerFactoryBean : Building JPA container EntityManagerFactory for persistence unit 'default'
2017-05-13 21:15:22.404  INFO 9745 --- [           main] o.hibernate.jpa.internal.util.LogHelper  : HHH000204: Processing PersistenceUnitInfo [
    name: default
    ...]
2017-05-13 21:15:22.468  INFO 9745 --- [           main] org.hibernate.Version                    : HHH000412: Hibernate Core {5.2.10.Final}
2017-05-13 21:15:22.470  INFO 9745 --- [           main] org.hibernate.cfg.Environment            : HHH000206: hibernate.properties not found
2017-05-13 21:15:22.503  INFO 9745 --- [           main] o.hibernate.annotations.common.Version   : HCANN000001: Hibernate Commons Annotations {5.0.1.Final}
2017-05-13 21:15:22.628  INFO 9745 --- [           main] org.hibernate.dialect.Dialect            : HHH000400: Using dialect: org.hibernate.dialect.PostgreSQL94Dialect
2017-05-13 21:15:22.737  INFO 9745 --- [           main] o.h.e.j.e.i.LobCreatorBuilderImpl        : HHH000424: Disabling contextual LOB creation as createClob() method threw error : java.lang.reflect.InvocationTargetException
2017-05-13 21:15:22.739  INFO 9745 --- [           main] org.hibernate.type.BasicTypeRegistry     : HHH000270: Type registration [java.util.UUID] overrides previous : org.hibernate.type.UUIDBinaryType@1e008f36
2017-05-13 21:15:23.195  INFO 9745 --- [           main] j.LocalContainerEntityManagerFactoryBean : Initialized JPA EntityManagerFactory for persistence unit 'default'
2017-05-13 21:15:23.645  INFO 9745 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@319b92f3: startup date [Sat May 13 21:15:20 EEST 2017]; root of context hierarchy
2017-05-13 21:15:23.697  INFO 9745 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[],methods=[POST]}" onto public void ua.alekstar.moneysaver.rest.AccountJsonRestController.post(ua.alekstar.moneysaver.rest.account.Account)
2017-05-13 21:15:23.698  INFO 9745 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[],methods=[GET]}" onto public ua.alekstar.moneysaver.rest.account.Accounts ua.alekstar.moneysaver.rest.AccountJsonRestController.get(java.lang.Long)
2017-05-13 21:15:23.698  INFO 9745 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[],methods=[PUT]}" onto public void ua.alekstar.moneysaver.rest.AccountJsonRestController.put(ua.alekstar.moneysaver.rest.account.Account)
2017-05-13 21:15:23.698  INFO 9745 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[],methods=[DELETE]}" onto public void ua.alekstar.moneysaver.rest.AccountJsonRestController.delete(java.lang.Long)
2017-05-13 21:15:23.700  WARN 9745 --- [           main] ationConfigEmbeddedWebApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'requestMappingHandlerMapping' defined in class path resource [org/springframework/boot/autoconfigure/web/WebMvcAutoConfiguration$EnableWebMvcConfiguration.class]: Invocation of init method failed; nested exception is java.lang.IllegalStateException: Ambiguous mapping. Cannot map '/json/currency' method 
public void ua.alekstar.moneysaver.rest.CurrencyJsonRestController.post(ua.alekstar.moneysaver.rest.currency.Currency)
to {[],methods=[POST]}: There is already '/json/account' bean method
public void ua.alekstar.moneysaver.rest.AccountJsonRestController.post(ua.alekstar.moneysaver.rest.account.Account) mapped.
2017-05-13 21:15:23.701  INFO 9745 --- [           main] j.LocalContainerEntityManagerFactoryBean : Closing JPA EntityManagerFactory for persistence unit 'default'
2017-05-13 21:15:23.703  INFO 9745 --- [           main] o.apache.catalina.core.StandardService   : Stopping service Tomcat
2017-05-13 21:15:23.716  INFO 9745 --- [           main] utoConfigurationReportLoggingInitializer : 

Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled.
2017-05-13 21:15:23.722 ERROR 9745 --- [           main] o.s.boot.SpringApplication               : Application startup failed

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'requestMappingHandlerMapping' defined in class path resource [org/springframework/boot/autoconfigure/web/WebMvcAutoConfiguration$EnableWebMvcConfiguration.class]: Invocation of init method failed; nested exception is java.lang.IllegalStateException: Ambiguous mapping. Cannot map '/json/currency' method 
public void ua.alekstar.moneysaver.rest.CurrencyJsonRestController.post(ua.alekstar.moneysaver.rest.currency.Currency)
to {[],methods=[POST]}: There is already '/json/account' bean method
public void ua.alekstar.moneysaver.rest.AccountJsonRestController.post(ua.alekstar.moneysaver.rest.account.Account) mapped.
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1628) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:866) ~[spring-context-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:542) ~[spring-context-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:737) [spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:370) [spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:314) [spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1162) [spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1151) [spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
    at ua.alekstar.moneysaver.MoneysaverApplication.main(MoneysaverApplication.java:10) [classes/:na]
Caused by: java.lang.IllegalStateException: Ambiguous mapping. Cannot map '/json/currency' method 
public void ua.alekstar.moneysaver.rest.CurrencyJsonRestController.post(ua.alekstar.moneysaver.rest.currency.Currency)
to {[],methods=[POST]}: There is already '/json/account' bean method
public void ua.alekstar.moneysaver.rest.AccountJsonRestController.post(ua.alekstar.moneysaver.rest.account.Account) mapped.
    at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping$MappingRegistry.assertUniqueMethodMapping(AbstractHandlerMethodMapping.java:576) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping$MappingRegistry.register(AbstractHandlerMethodMapping.java:540) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.registerHandlerMethod(AbstractHandlerMethodMapping.java:264) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.detectHandlerMethods(AbstractHandlerMethodMapping.java:250) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.initHandlerMethods(AbstractHandlerMethodMapping.java:214) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.afterPropertiesSet(AbstractHandlerMethodMapping.java:184) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.afterPropertiesSet(RequestMappingHandlerMapping.java:127) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1687) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1624) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    ... 16 common frames omitted


Process finished with exit code 1

After I remove one of the REST controllers the application runs successfully. What should I do to solve this issue?

Why are you using CurrencyService in both of your controllers?

@RestController("/json/currency") is different from 
@RestController 
@RequestMapping("/json/currency") 
Read @RestController documentation here https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/bind/annotation/RestController.html
change your 
declaration like this
@RestController 
@RequestMapping("......")  in both the classes. It should work

This was the greatest eye opener for me today. I got blinded over these annotations until I made the blunder of assigning path to @RestController

@WinterSoldier glad it helped :)

Since this answer appears on top of google searches, and my problem was a bit different, I am posting my solution:
I got the Spring Boot Ambiguous mapping. Cannot map method error.
The problem:
I had two controller methods with same @RequestMapping which were conflicting. Copy/paste mistake :)
The fix:
Change to appropriate @RequestMapping.
