Add javadoc documentation to Trustworthiness class

pgpainless-core/src/main/java/org/pgpainless/algorithm/Trustworthiness.java

@@ -4,6 +4,11 @@
 
 package org.pgpainless.algorithm;
 
+/**
+ * Facade class for {@link org.bouncycastle.bcpg.sig.TrustSignature}.
+ * A trust signature subpacket marks the trustworthiness of a certificate and defines its capabilities to act
+ * as a trusted introducer.
+ */
 public class Trustworthiness {
 
     private final int amount;
@@ -18,34 +23,82 @@ public class Trustworthiness {
         this.depth = capDepth(depth);
     }
 
+    /**
+     * Get the trust amount.
+     * This value means how confident the issuer of the signature is in validity of the binding.
+     *
+     * @return trust amount
+     */
     public int getAmount() {
         return amount;
     }
 
+    /**
+     * Get the depth of the trust signature.
+     * This value controls, whether the certificate can act as a trusted introducer.
+     *
+     * @return depth
+     */
     public int getDepth() {
         return depth;
     }
 
+    /**
+     * Returns true, if the trust amount is equal to 0.
+     * This means the key is not trusted.
+     *
+     * Otherwise return false
+     * @return true if untrusted
+     */
     public boolean isNotTrusted() {
         return getAmount() == NOT_TRUSTED;
     }
 
+    /**
+     * Return true if the certificate is at least marginally trusted.
+     * That is the case, if the trust amount is greater than 0.
+     *
+     * @return true if the cert is at least marginally trusted
+     */
     public boolean isMarginallyTrusted() {
         return getAmount() > NOT_TRUSTED;
     }
 
+    /**
+     * Return true if the certificate is fully trusted. That is the case if the trust amount is
+     * greater than or equal to 120.
+     *
+     * @return true if the cert is fully trusted
+     */
     public boolean isFullyTrusted() {
         return getAmount() >= THRESHOLD_FULLY_CONVINCED;
     }
 
+    /**
+     * Return true, if the cert is an introducer. That is the case if the depth is greater 0.
+     *
+     * @return true if introducer
+     */
     public boolean isIntroducer() {
         return getDepth() >= 1;
     }
 
+    /**
+     * Return true, if the certified cert can introduce certificates with trust depth of <pre>otherDepth</pre>.
+     *
+     * @param otherDepth other certifications trust depth
+     * @return true if the cert can introduce the other
+     */
     public boolean canIntroduce(int otherDepth) {
         return getDepth() > otherDepth;
     }
 
+    /**
+     * Return true, if the certified cert can introduce certificates with the given <pre>other</pre> trust depth.
+     *
+     * @param other other certificates trust depth
+     * @return true if the cert can introduce the other
+     */
     public boolean canIntroduce(Trustworthiness other) {
         return canIntroduce(other.getDepth());
     }
@@ -107,13 +160,13 @@ public class Trustworthiness {
         }
 
         /**
-         * The key is a level <pre>n</pre> meta introducer.
+         * The key is a meta introducer of depth <pre>n</pre>.
          * This key can introduce meta introducers of depth <pre>n - 1</pre>.
          *
          * @param n depth
          * @return trust
          */
-        public Trustworthiness levelNIntroducer(int n) {
+        public Trustworthiness metaIntroducerOfDepth(int n) {
             return new Trustworthiness(amount, n);
         }
     }