add rudimentary toString implementations

Author: yuzawa-san

iabgpp-encoder/src/main/java/com/iab/gpp/encoder/GppModel.java

@@ -495,5 +495,14 @@ public void decode(String encodedString) {
     this.decoded = false;
   }
 
+  public String toString() {
+    List<Integer> sectionIds = getSectionIds();
+    List<String> pieces = new ArrayList<>(sectionIds.size());
+    for (Integer sectionId : sectionIds) {
+      pieces.add(getSection(sectionId).toString());
+    }
+    return pieces.toString();
+  }
+
 
 }

iabgpp-encoder/src/main/java/com/iab/gpp/encoder/section/AbstractLazilyEncodableSection.java

@@ -1,6 +1,7 @@
 package com.iab.gpp.encoder.section;
 
 import java.util.List;
+import javax.swing.plaf.synth.SynthProgressBarUI;
 import com.iab.gpp.encoder.error.InvalidFieldException;
 import com.iab.gpp.encoder.segment.EncodableSegment;
 
@@ -93,4 +94,13 @@ public void decode(CharSequence encodedString) {
     this.decoded = false;
   }
 
+  public String toString() {
+    StringBuilder sb = new StringBuilder();
+    sb.append("{id=").append(getId()).append(", name=").append(getName()).append(", version=").append(getVersion());
+    for (EncodableSegment segment: segments) {
+      sb.append(", ").append(segment.toString());
+    }
+    sb.append('}');
+    return sb.toString();
+  }
 }

iabgpp-encoder/src/main/java/com/iab/gpp/encoder/segment/AbstractLazilyEncodableSegment.java

@@ -85,5 +85,16 @@ public void decode(CharSequence encodedString) {
     this.decoded = false;
   }
 
+  public String toString() {
+    StringBuilder sb = new StringBuilder();
+    sb.append("{name=").append(getClass().getSimpleName());
+    for (String field : fields.getNames()) {
+      if (hasField(field)) {
+        sb.append(", ").append(field).append('=').append(getFieldValue(field));
+      }
+    }
+    sb.append('}');
+    return sb.toString();
+  }
 
 }