Prices with a decimal comma should be accepted

[php-coder]

Reported by our user:

In my country we use decimal comma instead of decimal point for currency. So at first I tried “0,75" instead of “0.75” but that did not work:

The warning could be confusing for other (international) users, not clear what exactly was invalid in my case. Maybe you can set or add a warning for explaining what separator character to use. Or make it possible to use both comma and point.

[php-coder]

We should accept both cases and also we should cover all places where user can specify price.

[php-coder]

Can be useful:

• https://vianneyfaivre.com/tech/spring-forms-how-to-use-data-binders
• https://stackoverflow.com/questions/42056112/spring-mvc-controller-numberformat-annotation-pattern-issue-in-bigdecimal
• https://docs.spring.io/spring-framework/docs/5.1.x/spring-framework-reference/core.html#beans-beans-conversion

[php-coder]

Discover a bug: when I specify michel price with a comma on the series info page, the server fails with:

Caused by: java.lang.NumberFormatException: null
        at java.math.BigDecimal.<init>(BigDecimal.java:494) ~[na:1.8.0_151]
        at java.math.BigDecimal.<init>(BigDecimal.java:383) ~[na:1.8.0_151]
        at java.math.BigDecimal.<init>(BigDecimal.java:806) ~[na:1.8.0_151]
        at ru.mystamps.web.support.spring.mvc.PatchRequest.bigDecimalValue(PatchRequest.java:62) ~[classes!/:0.4.6-SNAPSHOT]
        at ru.mystamps.web.feature.series.RestSeriesController.updateSeries(RestSeriesController.java:91) ~[classes!/:0.4.6-SNAPSHOT]
        at ru.mystamps.web.feature.series.RestSeriesController$$FastClassBySpringCGLIB$$852da25.invoke(<generated>) ~[classes!/:0.4.6-SNAPSHOT]
        at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218) ~[spring-core-5.1.20.RELEASE.jar!/:5.1.20.RELEASE]
        at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:752) ~[spring-aop-5.1.20.RELEASE.jar!/:5.1.20.RELEASE]
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) ~[spring-aop-5.1.20.RELEASE.jar!/:5.1.20.RELEASE]
        at org.springframework.validation.beanvalidation.MethodValidationInterceptor.invoke(MethodValidationInterceptor.java:119) ~[spring-context-5.1.20.RELEASE.jar!/:5.1.20.RELEASE]
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.20.RELEASE.jar!/:5.1.20.RELEASE]
        at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:691) ~[spring-aop-5.1.20.RELEASE.jar!/:5.1.20.RELEASE]
        at ru.mystamps.web.feature.series.RestSeriesController$$EnhancerBySpringCGLIB$$621c0aa2.updateSeries(<generated>) ~[classes!/:0.4.6-SNAPSHOT]