ICU-21480 BRS69 ICU4J API signature file

- Supplied missing API comment to com.ibm.icu.nubmer.Precision#trailingZeroDisplay(TrailingZeroDisplay)
- Generated API signature file for ICU4J 69.1 and added to the repository
- Delete ICU4J 59 API signature file
- Deleted unused icu4j/eclipse-build/build.properties. The folder eclipse-build was deleted, but someone worked on ICU version seemed to add it back again. Delete it again.

icu4j/eclipse-build/build.properties

diff --git a/icu4j/eclipse-build/build.properties b/icu4j/eclipse-build/build.properties
deleted file mode 100644
index 814c0b9..0000000
--- a/icu4j/eclipse-build/build.properties
+++ /dev/null
@@ -1,9 +0,0 @@
-# Copyright (C) 2016 and later: Unicode, Inc. and others.
-# License & terms of use: http://www.unicode.org/copyright.html
-#*******************************************************************************
-#* Copyright (C) 2010-2016, International Business Machines Corporation and    *
-#* others. All Rights Reserved.                                                *
-#*******************************************************************************
-icu4j.plugin.impl.version.string=69.1.0
-copyright.eclipse=(C) 2016 and later: Unicode, Inc. and others. License & terms of use: http://www.unicode.org/copyright.html
-icu4j.data.version.number=69

icu4j/main/classes/core/src/com/ibm/icu/number/Precision.java

diff --git a/icu4j/main/classes/core/src/com/ibm/icu/number/Precision.java b/icu4j/main/classes/core/src/com/ibm/icu/number/Precision.java
index 31aded5..15fd8f2 100644
--- a/icu4j/main/classes/core/src/com/ibm/icu/number/Precision.java
+++ b/icu4j/main/classes/core/src/com/ibm/icu/number/Precision.java
@@ -339,6 +339,13 @@ public static CurrencyPrecision currency(CurrencyUsage currencyUsage) {
         }
     }
 
+    /**
+     * Configure how trailing zeros are displayed on numbers. For example, to hide trailing zeros
+     * when the number is an integer, use HIDE_IF_WHOLE.
+     *
+     * @param trailingZeroDisplay Option to configure the display of trailing zeros.
+     * @draft ICU 69
+     */
     public Precision trailingZeroDisplay(TrailingZeroDisplay trailingZeroDisplay) {
         Precision result = this.createCopy();
         result.trailingZeroDisplay = trailingZeroDisplay;

icu4j/tools/build/icu4j59.api3.gz

diff --git a/icu4j/tools/build/icu4j59.api3.gz b/icu4j/tools/build/icu4j59.api3.gz
deleted file mode 100644
index 1e44db0..0000000
--- a/icu4j/tools/build/icu4j59.api3.gz
+++ /dev/null
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icu4j/tools/build/icu4j69.api3.gz

diff --git a/icu4j/tools/build/icu4j69.api3.gz b/icu4j/tools/build/icu4j69.api3.gz
new file mode 100644
index 0000000..d4d6b26
--- /dev/null
+++ b/icu4j/tools/build/icu4j69.api3.gz
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