moved post targets to an enum, in order to have more type safety, this might be changed in the future

added validation check when a feature is enabled, in order to notify which configuration is missing for this feature to function properly

abstracto-application/abstracto-modules/modmail/modmail-int/src/main/java/dev/sheldan/abstracto/modmail/config/ModMailFeature.java

@@ -0,0 +1,32 @@
+package dev.sheldan.abstracto.modmail.config;
+
+import dev.sheldan.abstracto.core.config.FeatureConfig;
+import dev.sheldan.abstracto.core.config.FeatureEnum;
+import dev.sheldan.abstracto.core.config.PostTargetEnum;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+import java.util.Arrays;
+import java.util.List;
+
+@Component
+public class ModMailFeature implements FeatureConfig {
+
+    @Autowired
+    private ModMailLoggingFeature modMailLoggingFeature;
+
+    @Override
+    public FeatureEnum getFeature() {
+        return ModMailFeatures.MOD_MAIL;
+    }
+
+    @Override
+    public List<FeatureConfig> getDependantFeatures() {
+        return Arrays.asList(modMailLoggingFeature);
+    }
+
+    @Override
+    public List<PostTargetEnum> getRequiredPostTargets() {
+        return Arrays.asList(ModMailPostTargets.MOD_MAIL_PING);
+    }
+}

abstracto-application/abstracto-modules/modmail/modmail-int/src/main/java/dev/sheldan/abstracto/modmail/config/ModMailFeatures.java

@@ -0,0 +1,18 @@
+package dev.sheldan.abstracto.modmail.config;
+
+import dev.sheldan.abstracto.core.config.FeatureEnum;
+
+public enum ModMailFeatures implements FeatureEnum {
+    MOD_MAIL("modmail"), MOD_MAIL_LOGGING("modmail_logging");
+
+    private String key;
+
+    ModMailFeatures(String key) {
+        this.key = key;
+    }
+
+    @Override
+    public String getKey() {
+        return this.key;
+    }
+}

abstracto-application/abstracto-modules/modmail/modmail-int/src/main/java/dev/sheldan/abstracto/modmail/config/ModMailLoggingFeature.java

@@ -0,0 +1,32 @@
+package dev.sheldan.abstracto.modmail.config;
+
+import dev.sheldan.abstracto.core.config.FeatureConfig;
+import dev.sheldan.abstracto.core.config.FeatureEnum;
+import dev.sheldan.abstracto.core.config.PostTargetEnum;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+import java.util.Arrays;
+import java.util.List;
+
+@Component
+public class ModMailLoggingFeature implements FeatureConfig {
+
+    @Autowired
+    private ModMailFeature modMailFeature;
+
+    @Override
+    public FeatureEnum getFeature() {
+        return ModMailFeatures.MOD_MAIL_LOGGING;
+    }
+
+    @Override
+    public List<FeatureConfig> getRequiredFeatures() {
+        return Arrays.asList(modMailFeature);
+    }
+
+    @Override
+    public List<PostTargetEnum> getRequiredPostTargets() {
+        return Arrays.asList(ModMailPostTargets.MOD_MAIL_LOG);
+    }
+}

abstracto-application/abstracto-modules/modmail/modmail-int/src/main/java/dev/sheldan/abstracto/modmail/config/ModMailPostTargets.java

@@ -0,0 +1,15 @@
+package dev.sheldan.abstracto.modmail.config;
+
+import dev.sheldan.abstracto.core.config.PostTargetEnum;
+import lombok.Getter;
+
+@Getter
+public enum  ModMailPostTargets implements PostTargetEnum {
+    MOD_MAIL_PING("modmailPing"), MOD_MAIL_LOG("modmailLog");
+
+    private String key;
+
+    ModMailPostTargets(String key) {
+        this.key = key;
+    }
+}

abstracto-application/abstracto-modules/modmail/modmail-int/src/main/java/dev/sheldan/abstracto/modmail/config/ModMailProperties.java

@@ -0,0 +1,9 @@
+package dev.sheldan.abstracto.modmail.config;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.PropertySource;
+
+@Configuration
+@PropertySource("classpath:config/modmail.properties")
+public class ModMailProperties {
+}