Why does Maven clean remove my codes that I have coded?

Question

Background: I am using an appian-plugin where Java is the main language to do customizations.

I have inserted codes into a class that belongs to the plugin working space and whenever I maven clean install, at the clean process, my codes will be gone. I heard from other colleagues that it could be because of a .wsdl file that automatically generates files when it's redeployed? Kindly do advise. Thank you.

This is the extract of code that I'm trying to insert.

public static Comparator <DummyFormData> sortWageIncrementFinancialYr = new Comparator <Dummy>() {
        public int compare(DummyFormData u1, DummyFormData u2) {
            int compare1 = u1.financialYr.get(0);
            int compare2 = u2.financialYr.get(0);
            
            Boolean result = compare1 > compare2;
            return result  ? 1 : -1;
        }
        
    };

.wsdl codes relating to this

 <xs:complexType name="DummyFormData">
                <xs:sequence>
                <xs:element name="financialYr" type="xs:int" nillable="true" minOccurs="0" maxOccurs="unbounded"/>
                <xs:element name="totalWagesOfWorkers" type="xs:decimal" nillable="true" minOccurs="0" maxOccurs="unbounded"/>
                <xs:element name="numOfWorkers" type="xs:int" nillable="true" minOccurs="0" maxOccurs="unbounded"/>
                </xs:sequence>
                 </xs:complexType>