New rule: Avoid String.valueOf(arg) where arg is a String

[dgroup]

Summary

Key	Value
Rule	AvoidStringValueOfForStringArg
Ruleset	io/github/dgroup/arch4u/pmd/....xml
Category	Error Prone
Framework	...
Since	0.3.+
Incidents in past at my experience	2+
Template	false

Rule definition

<rule name="AvoidStringValueOfForStringArg"
      since="0.3.+"
      language="java"
      externalInfoUrl="https://github.com/dgroup/arch4u-pmd/discussions/..."
      message="...: https://github.com/dgroup/arch4u-pmd/discussions/..."
      class="io.github.dgroup.arch4u.pmd....">
    <priority>3</priority>
    <properties>
      <property name="types" value="java.lang.String|..."/>
    </properties>
</rule>

Why?

.consumes(String.valueOf(MediaType.APPLICATION_JSON))